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PDP-11 Absolute Loader

2025-03-07T19:43:41Z

Jdl: /* Further reading */ Reference to assembly listing for Absolute Loader

The '''PDP-11 Absolute Loader''' is a short [[program]] designed to be loaded into the [[main memory]] of a [[PDP-11]] by the [[PDP-11 Bootstrap Loader]] (most [[object code|binary]] copies of the absolute loader are in the format expected by the bootstrap loader); it in turn is then run to load some other program into the machine.

The bootstrap loader is designed to be absolutely as short as possible (since it is manually toggled in via the [[front panel]]), and therefore has limitations, including how long a program can be loaded using it, and where in memory that program can be placed; the absolute loader relaxes both of those limitations.

The initial version of the absolute loader had three different operating modes, controlled by the contents of the [[switch register]]. If '0', it operated 'normally'. If '1', each block is loaded immediately following the previous block (i.e. the [[address]] in the block header is ignored). If 'xxxxx1' (in binary), the block is loaded at the address given in the high bits of the switch register. For later PDP-11's, which did not have a switch register, a modified version is required.

==Absolute Loader format==

The format of absolute loader input is that it consists of an arbitrary number of blocks, each of which has the following format:

* Leader (all [[byte]]s 0)
* Start marker (1 byte, value '1')
* Pad (1 byte, value '0')
* Low byte count (1 byte)
* High byte count (1 byte)
* Low load address (1 byte)
* High load address (1 byte)
* Program to be loaded
* [[Checksum]] (1 byte)

The optional leader is because the absolute loader was originally for loading programs held on [[paper tape]]. The byte count includes the header starting with the 'start marker' (i.e. 6 bytes), but does ''not'' include the checksum byte.

The checksum is the low-order byte of the negation of the sum of all the bytes in a block; when all the bytes of a block, including the checksum, are added together, the low-order byte of the result should be zero (if the block has been read correctly).

A block of length 6 (i.e. only the header) marks the end of the input. If the address is odd, the absolute loader [[halt]]s; if even, it [[jump]]s to the address given in the last block.

This format, denominated by the ending ".LDA" in [[file]] names, continued to be used with PDP-11's for the duration of their life.

==Further reading==

Usage of the Absolute Loader is documented in some detail in the "PDP-11 Paper Tape Software Programming Handbook" (DEC-11-GGPB-D), pp. 6-8 to 6-12.

An assembly listing for the Absolute Loader is given in "LISTING OF PDP-11 ABSOLUTE LOADER" (DEC-11-UABLA-A-LA).

[[Category: PDP-11 Software]]
[[Category: PDP-11 File Formats]]

PDP-11 Bootstrap Loader

2025-03-05T04:48:40Z

Jdl: Slightly clearer description of xx

The '''PDP-11 Bootstrap Loader''' is a short [[program]] designed to be loaded into the [[main memory]] on a [[PDP-11]] via the [[front panel]]; it is then run to load an initial program into the machine. I.e. it is a way of [[bootstrap]]ping a totally empty machine, one with no [[Read-only memory|ROM]].

It is designed to be absolutely as short as possible (since it is manually toggled in via the [[switch register]]), and therefore has limitations, including how long a program can be loaded using it, and where in memory that program can be placed. The usual program to load with it is the [[PDP-11 Absolute Loader]], which relaxes both of those limitations.

The original bootstrap loader is [[self-modifying code]], since this allows a very short program. The program is not directly self-modifying; rather, the nature of its input is such that it modifies the bootstrap loader as it is read in. (Most bootstrap loader input files eventually restore the bootstrap loader to its original condition, allowing it to be re-used.)

==Program==

The bootstrap loader contains two locations which are modified by reading the input: the first is a [[pointer]] to the [[buffer]] in which to place data being read in; the second is a [[branch]] back to the beginning of the data input [[loop]].

The program starts with the pointer set to itself, so the blank leader at the start of the data for the bootstrap loader (originally contained on [[paper tape]]s) starts with a special leader code which causes this to be left un-changed.

The buffer pointer is then modified to point it slightly before the bootstrap loader in memory, so at the end of the load the newly loaded code then progressively overlays the first several [[instruction]]s of the bootstrap loader itself, finally patching the buffer pointer to point at the branch instruction, which is then modified to jump to the newly loaded code.

===Code===

This is the actual bootstrap program:

<pre>
LOAD=xx7400 ; Buffer start address

.=LOAD+0344 ; Start address of bootstrap loader (xx7744)

xx7744 016701 START: MOV DEVICE, R1 ; Get reader CSR address
xx7746 000026
xx7750 012702 LOOP: MOV #.-LOAD+2, R2 ; Get buffer pointer
xx7752 000352 ; (<--- pointer to buffer)
xx7754 005211 INC @R1 ; Enable the paper tape reader
xx7756 105711 WAIT: TSTB @R1 ; Wait until data available
xx7760 100376 BPL WAIT
xx7762 116162 MOVB 2(R1), LOAD(R2) ; Transfer byte to buffer
xx7764 000002
xx7766 xx7400
xx7770 005267 INC LOOP+2 ; Increment pointer to buffer
xx7772 177756
xx7774 000765 BR LOOP ; Continue reading (<--- modified branch instruction)
xx7776 yyyyyy DEVICE: yyyyyy ; Paper tape reader CSR address
</pre>

When inputting the bootstrap program, the first instruction should be placed at location xx7744,
where xx is replaced with the address of the highest memory bank available according to the following table:

{| class="wikitable" style="text-align:center;"
! Memory Bank
! Total Memory
! Bootstrap<br>Location
! xx Value
|-
| 0
| 4K
| 017744
| 01
|-
| 1
| 8K
| 037744
| 03
|-
| 2
| 12K
| 057744
| 05
|-
| 3
| 16K
| 077744
| 07
|-
| 4
| 20K
| 117744
| 11
|-
| 5
| 24K
| 137744
| 13
|-
| 6
| 28K
| 157744
| 15
|}

Note also that, when inputting the word at xx7766, the value (xx7400) should be similarly adjusted.

The value of the word at location xx7776 (yyyyyy) should be replaced with the CSR address of the desired paper tape reader, e.g.:

{| class="wikitable"
|-
| Console Paper Tape Reader
| 177560
|-
| High-Speed Paper Taper Reader
| 177550
|}

==Bootstrap Loader format==

The format of boostrap loader input is as follows:

* Leader (all bytes 0351)
* Load offset (1 byte)
* Program to be loaded (up to 0344 bytes)
* Copy of boostrap loader (first 6 bytes)
* Offset to branch (1 byte)
* Branch modification (1 byte)

==Others==

Several PDP-11 bootstrap ROMs, e.g. the [[BM792 ROM|BM792-YA]], BM792-YK and [[BM873 ROM]] are prepared to read programs in bootstrap loader format. The code in them is obviously not self-modifying, but reacts to the bootstrap loader input format to produce the same effects.

[[QBUS CPU ODT‎|ODT]] in the [[LSI-11 CPUs]] also has a command to load programs in bootstrap loader format.

==Further reading==

The Bootstrap Loader is documented in some detail in the "paper tape software programming handbook" (DEC-11-GGPB-D), pp. 6-1 to 6-8.

[[Category: PDP-11 Software]]
[[Category: PDP-11 File Formats]]

PDP-11 Bootstrap Loader

2025-03-05T04:39:36Z

Jdl: Transfer *byte* to buffer, not word

The '''PDP-11 Bootstrap Loader''' is a short [[program]] designed to be loaded into the [[main memory]] on a [[PDP-11]] via the [[front panel]]; it is then run to load an initial program into the machine. I.e. it is a way of [[bootstrap]]ping a totally empty machine, one with no [[Read-only memory|ROM]].

It is designed to be absolutely as short as possible (since it is manually toggled in via the [[switch register]]), and therefore has limitations, including how long a program can be loaded using it, and where in memory that program can be placed. The usual program to load with it is the [[PDP-11 Absolute Loader]], which relaxes both of those limitations.

The original bootstrap loader is [[self-modifying code]], since this allows a very short program. The program is not directly self-modifying; rather, the nature of its input is such that it modifies the bootstrap loader as it is read in. (Most bootstrap loader input files eventually restore the bootstrap loader to its original condition, allowing it to be re-used.)

==Program==

The bootstrap loader contains two locations which are modified by reading the input: the first is a [[pointer]] to the [[buffer]] in which to place data being read in; the second is a [[branch]] back to the beginning of the data input [[loop]].

The program starts with the pointer set to itself, so the blank leader at the start of the data for the bootstrap loader (originally contained on [[paper tape]]s) starts with a special leader code which causes this to be left un-changed.

The buffer pointer is then modified to point it slightly before the bootstrap loader in memory, so at the end of the load the newly loaded code then progressively overlays the first several [[instruction]]s of the bootstrap loader itself, finally patching the buffer pointer to point at the branch instruction, which is then modified to jump to the newly loaded code.

===Code===

This is the actual bootstrap program:

<pre>
LOAD=xx7400 ; Buffer start address

.=LOAD+0344 ; Start address of bootstrap loader (xx7744)

xx7744 016701 START: MOV DEVICE, R1 ; Get reader CSR address
xx7746 000026
xx7750 012702 LOOP: MOV #.-LOAD+2, R2 ; Get buffer pointer
xx7752 000352 ; (<--- pointer to buffer)
xx7754 005211 INC @R1 ; Enable the paper tape reader
xx7756 105711 WAIT: TSTB @R1 ; Wait until data available
xx7760 100376 BPL WAIT
xx7762 116162 MOVB 2(R1), LOAD(R2) ; Transfer byte to buffer
xx7764 000002
xx7766 xx7400
xx7770 005267 INC LOOP+2 ; Increment pointer to buffer
xx7772 177756
xx7774 000765 BR LOOP ; Continue reading (<--- modified branch instruction)
xx7776 yyyyyy DEVICE: yyyyyy ; Paper tape reader CSR address
</pre>

When inputting the bootstrap program, the first word is loaded at location xx7744, where xx is replaced with the
address of the highest memory bank available according to the following table:

{| class="wikitable" style="text-align:center;"
! Memory Bank
! Total Memory
! Bootstrap<br>Location
! xx Value
|-
| 0
| 4K
| 017744
| 01
|-
| 1
| 8K
| 037744
| 03
|-
| 2
| 12K
| 057744
| 05
|-
| 3
| 16K
| 077744
| 07
|-
| 4
| 20K
| 117744
| 11
|-
| 5
| 24K
| 137744
| 13
|-
| 6
| 28K
| 157744
| 15
|}

Note also that, when inputting the word at xx7766, the value (xx7400) should be similarly adjusted.

The value of the word at location xx7776 (yyyyyy) should be replaced with the CSR address of the desired paper tape reader, e.g.:

{| class="wikitable"
|-
| Console Paper Tape Reader
| 177560
|-
| High-Speed Paper Taper Reader
| 177550
|}

==Bootstrap Loader format==

The format of boostrap loader input is as follows:

* Leader (all bytes 0351)
* Load offset (1 byte)
* Program to be loaded (up to 0344 bytes)
* Copy of boostrap loader (first 6 bytes)
* Offset to branch (1 byte)
* Branch modification (1 byte)

==Others==

Several PDP-11 bootstrap ROMs, e.g. the [[BM792 ROM|BM792-YA]], BM792-YK and [[BM873 ROM]] are prepared to read programs in bootstrap loader format. The code in them is obviously not self-modifying, but reacts to the bootstrap loader input format to produce the same effects.

[[QBUS CPU ODT‎|ODT]] in the [[LSI-11 CPUs]] also has a command to load programs in bootstrap loader format.

==Further reading==

The Bootstrap Loader is documented in some detail in the "paper tape software programming handbook" (DEC-11-GGPB-D), pp. 6-1 to 6-8.

[[Category: PDP-11 Software]]
[[Category: PDP-11 File Formats]]

PDP-11 Bootstrap Loader

2025-03-05T04:36:47Z

Jdl: Replaced bootstrap code with valid macro11 assembly that more closely matches the DEC documentation. Replaced "0x" placeholder text with "xx" to avoid confusion with C hex prefix. Added tables of possible xx and yyyyyy values.

The '''PDP-11 Bootstrap Loader''' is a short [[program]] designed to be loaded into the [[main memory]] on a [[PDP-11]] via the [[front panel]]; it is then run to load an initial program into the machine. I.e. it is a way of [[bootstrap]]ping a totally empty machine, one with no [[Read-only memory|ROM]].

It is designed to be absolutely as short as possible (since it is manually toggled in via the [[switch register]]), and therefore has limitations, including how long a program can be loaded using it, and where in memory that program can be placed. The usual program to load with it is the [[PDP-11 Absolute Loader]], which relaxes both of those limitations.

The original bootstrap loader is [[self-modifying code]], since this allows a very short program. The program is not directly self-modifying; rather, the nature of its input is such that it modifies the bootstrap loader as it is read in. (Most bootstrap loader input files eventually restore the bootstrap loader to its original condition, allowing it to be re-used.)

==Program==

The bootstrap loader contains two locations which are modified by reading the input: the first is a [[pointer]] to the [[buffer]] in which to place data being read in; the second is a [[branch]] back to the beginning of the data input [[loop]].

The program starts with the pointer set to itself, so the blank leader at the start of the data for the bootstrap loader (originally contained on [[paper tape]]s) starts with a special leader code which causes this to be left un-changed.

The buffer pointer is then modified to point it slightly before the bootstrap loader in memory, so at the end of the load the newly loaded code then progressively overlays the first several [[instruction]]s of the bootstrap loader itself, finally patching the buffer pointer to point at the branch instruction, which is then modified to jump to the newly loaded code.

===Code===

This is the actual bootstrap program:

<pre>
LOAD=xx7400 ; Buffer start address

.=LOAD+0344 ; Start address of bootstrap loader (xx7744)

xx7744 016701 START: MOV DEVICE, R1 ; Get reader CSR address
xx7746 000026
xx7750 012702 LOOP: MOV #.-LOAD+2, R2 ; Get buffer pointer
xx7752 000352 ; (<--- pointer to buffer)
xx7754 005211 INC @R1 ; Enable the paper tape reader
xx7756 105711 WAIT: TSTB @R1 ; Wait until data available
xx7760 100376 BPL WAIT
xx7762 116162 MOVB 2(R1), LOAD(R2) ; Transfer word to buffer
xx7764 000002
xx7766 xx7400
xx7770 005267 INC LOOP+2 ; Increment pointer to buffer
xx7772 177756
xx7774 000765 BR LOOP ; Continue reading (<--- modified branch instruction)
xx7776 yyyyyy DEVICE: yyyyyy ; Paper tape reader CSR address
</pre>

When inputting the bootstrap program, the first word is loaded at location xx7744, where xx is replaced with the
address of the highest memory bank available according to the following table:

{| class="wikitable" style="text-align:center;"
! Memory Bank
! Total Memory
! Bootstrap<br>Location
! xx Value
|-
| 0
| 4K
| 017744
| 01
|-
| 1
| 8K
| 037744
| 03
|-
| 2
| 12K
| 057744
| 05
|-
| 3
| 16K
| 077744
| 07
|-
| 4
| 20K
| 117744
| 11
|-
| 5
| 24K
| 137744
| 13
|-
| 6
| 28K
| 157744
| 15
|}

Note also that, when inputting the word at xx7766, the value (xx7400) should be similarly adjusted.

The value of the word at location xx7776 (yyyyyy) should be replaced with the CSR address of the desired paper tape reader, e.g.:

{| class="wikitable"
|-
| Console Paper Tape Reader
| 177560
|-
| High-Speed Paper Taper Reader
| 177550
|}

==Bootstrap Loader format==

The format of boostrap loader input is as follows:

* Leader (all bytes 0351)
* Load offset (1 byte)
* Program to be loaded (up to 0344 bytes)
* Copy of boostrap loader (first 6 bytes)
* Offset to branch (1 byte)
* Branch modification (1 byte)

==Others==

Several PDP-11 bootstrap ROMs, e.g. the [[BM792 ROM|BM792-YA]], BM792-YK and [[BM873 ROM]] are prepared to read programs in bootstrap loader format. The code in them is obviously not self-modifying, but reacts to the bootstrap loader input format to produce the same effects.

[[QBUS CPU ODT‎|ODT]] in the [[LSI-11 CPUs]] also has a command to load programs in bootstrap loader format.

==Further reading==

The Bootstrap Loader is documented in some detail in the "paper tape software programming handbook" (DEC-11-GGPB-D), pp. 6-1 to 6-8.

[[Category: PDP-11 Software]]
[[Category: PDP-11 File Formats]]

DEC card form factor

2021-10-16T03:07:00Z

Jdl: Added pointer to mechanical specifications in legacy DEC document hosted at bitsavers.

Many different [[DEC]] computers (e.g. [[PDP-8 family|PDP-8]], [[PDP-10]], [[PDP-11]]) used a standard set of board sizes, in part because they all used [[FLIP CHIP]]s.

The original small '''standard length''' FLIP CHIPs (used in the PDP-8 and [[KA10]] PDP-10 processor) had a total board size of 4.93 inches (from the far end of the edge connector contacts, to the handle end of the board) by 2.437 inches (from one side to the other). From this basic size, a large array of other sizes was built up.

A board of the same width, but approximately twice as long (8.43 inches) was referred to an an '''extended length''' board; many later M-series FLIP CHIPs used this format. A board of the short length, but twice as wide (5.187 inches) was referred to as a '''double height''' board; boards of this size are not common, but do exist.

(The 'height' does not refer to the distance from the edge with the handles, to the edge with the contacts, but rather to the distance from one side edge to the other; this is because these board were usually mounted vertically, with the side edges on the top and bottom.)

Extended length boards later came in multiples of two, four (10.457 inches) and six times the width of the small original board; these are usually called '''dual''', '''quad''' and '''hex''' height format boards.

Finally, as production processes improved, and leading signals from board to board became undesirable, even longer hex boards were introduced; these first appeared in the [[VAX-11/780]], and were called '''super hex''' boards within DEC.

==Specifications==

The mechanical specifications for single, dual and quad-height FLIP CHIP boards can be found in the [http://www.bitsavers.org/pdf/dec/handbooks/Digital_Logic_Handbook_1975-76.pdf Digital Logic Handbook 1975-76], p. 6-10.

==See also==

* [[DEC edge connector contact identification]]

[[Category: DEC Hardware]]

UNIBUS H854 header pinout

2021-10-16T02:45:22Z

Jdl: Fixed rendering of "By Class" table

DEC produced several boards (the M9014, an [[DEC card form factor|extended height dual card]], and the M9042 short dual card) cards to replace the standard BC11A [[UNIBUS]] cable. They plug into the same 'UNIBUS In' and 'UNIBUS Out' backplane slots as the BC11A, and contain three 2x20 headers for 40-conductor flat cables (known as H854 cables in DEC parlance); a pair of these cards, and three cables, perform the same role as a BC11A cable.

Both of these cards use the header pinout given below, so they may be used interchangeably. Following standard electrical engineering practise, every alternate wire in the flat cable is a ground: the active pins are B, D, F, J, L, N, R, T, V, X, Z, BB, DD, FF, JJ, LL, NN, RR, TT, VV (using the Berg header pin nomenclature).

==By class==

{| class="wikitable"
! Signal !! Assertion !! Termination !! BC11A pin !! Berg header pin
|-
| colspan="5" style="text-align:center;" | Initialization and Shutdown
|-
| DC LO || L || Slow || BF2 || J3-VV
|-
| AC LO || L || Slow || BF1 || J2-VV
|-
| INIT || L || Fast || AA1 || J3-Z
|-
| colspan="5" style="text-align:center;" | Arbitration
|-
| NPR || L || Fast || AS2 || J3-B
|-
| BR7 || L || Fast || AT2 || J3-F
|-
| BR6 || L || Fast || AU2 || J3-L
|-
| BR5 || L || Fast || BC1 || J3-R
|-
| BR4 || L || Fast || BD2 || J3-V
|-
| NPG || H || Grant || AU1 || J3-D
|-
| BG7 || H || Grant || AV1 || J3-J
|-
| BG6 || H || Grant || BA1 || J3-N
|-
| BG5 || H || Grant || BB1 || J3-T
|-
| BG4 || H || Grant || BE2 || J3-X
|-
| SACK || L || Fast || AR2 || J3-TT
|-
| colspan="5" style="text-align:center;" | Address
|-
| A00 || L || Fast || BH2 || J1-D
|-
| A01 || L || Fast || BH1 || J1-B
|-
| A02 || L || Fast || BJ2 || J1-J
|-
| A03 || L || Fast || BJ1 || J1-F
|-
| A04 || L || Fast || BK2 || J1-N
|-
| A05 || L || Fast || BK1 || J1-L
|-
| A06 || L || Fast || BL2 || J1-T
|-
| A07 || L || Fast || BL1 || J1-R
|-
| A08 || L || Fast || BM2 || J1-X
|-
| A09 || L || Fast || BM1 || J1-V
|-
| A10 || L || Fast || BN2 || J1-BB
|-
| A11 || L || Fast || BN1 || J1-Z
|-
| A12 || L || Fast || BP2 || J1-FF
|-
| A13 || L || Fast || BP1 || J1-DD
|-
| A14 || L || Fast || BR2 || J1-LL
|-
| A15 || L || Fast || BR1 || J1-JJ
|-
| A16 || L || Fast || BS2 || J1-RR
|-
| A17 || L || Fast || BS1 || J1-NN
|-
| colspan="5" style="text-align:center;" | Data
|-
| D00 || L || Fast || AC1 || J2-B
|-
| D01 || L || Fast || AD2 || J2-F
|-
| D02 || L || Fast || AD1 || J2-D
|-
| D03 || L || Fast || AE2 || J2-L
|-
| D04 || L || Fast || AE1 || J2-J
|-
| D05 || L || Fast || AF2 || J2-R
|-
| D06 || L || Fast || AF1 || J2-N
|-
| D07 || L || Fast || AH2 || J2-Z
|-
| D08 || L || Fast || AH1 || J2-T
|-
| D09 || L || Fast || AJ2 || J2-Z
|-
| D10 || L || Fast || AJ1 || J2-X
|-
| D11 || L || Fast || AK2 || J2-DD
|-
| D12 || L || Fast || AK1 || J2-BB
|-
| D13 || L || Fast || AL2 || J2-JJ
|-
| D14 || L || Fast || AL1 || J2-FF
|-
| D15 || L || Fast || AM2 || J2-NN
|-
| colspan="5" style="text-align:center;" | Control
|-
| C0 || L || Fast || BU2 || J3-NN
|-
| C1 || L || Fast || BT2 || J1-TT
|-
| PA || L || Fast || AM1 || J2-LL
|-
| PB || L || Fast || AN2 || J2-RR
|-
| BBSY || L || Fast || AP2 || J3-BB
|-
| MSYN || L || Fast || BV1 || J3-LL
|-
| INTR || L || Fast || AB1 || J3-FF
|-
| SSYN || L || Fast || BU1 || J3-JJ
|-
| colspan="5" style="text-align:center;" | Power
|-
| Ground || N/A || N/A || AB2
|-
| Ground || N/A || N/A || AC2
|-
| Ground || N/A || N/A || AN1
|-
| Ground || N/A || N/A || AP1
|-
| Ground || N/A || N/A || AR1
|-
| Ground || N/A || N/A || AS1
|-
| Ground || N/A || N/A || AT1
|-
| Ground || N/A || N/A || AV2
|-
| Ground || N/A || N/A || BB2
|-
| Ground || N/A || N/A || BC2
|-
| Ground || N/A || N/A || BD1
|-
| Ground || N/A || N/A || BE1
|-
| Ground || N/A || N/A || BT1
|-
| Ground || N/A || N/A || BV2
|-
| Ground || N/A || N/A || N/A || J1-VV
|-
| Ground || N/A || N/A || N/A || J2-TT
|-
| Ground || N/A || N/A || N/A || J3-DD
|-
| Ground || N/A || N/A || N/A || J3-RR
|-
| +5 || N/A || N/A || AA2
|-
| +5 || N/A || N/A || BA2
|-
| colspan="5" style="text-align:center;" | Other
|-
| No connection || N/A || N/A || BA2
|-
| No connection || N/A || N/A || BB2
|}

==By Berg pin==

{| class="wikitable"
! Signal !! Assertion !! Termination !! BC11A pin !! Berg header pin
|-
| colspan="5" style="text-align:center;" | Header J1
|-
| A01 || L || Fast || BH1 || J1-B
|-
| A00 || L || Fast || BH2 || J1-D
|-
| A03 || L || Fast || BJ1 || J1-F
|-
| A02 || L || Fast || BJ2 || J1-J
|-
| A05 || L || Fast || BK1 || J1-L
|-
| A04 || L || Fast || BK2 || J1-N
|-
| A07 || L || Fast || BL1 || J1-R
|-
| A06 || L || Fast || BL2 || J1-T
|-
| A09 || L || Fast || BM1 || J1-V
|-
| A08 || L || Fast || BM2 || J1-X
|-
| A11 || L || Fast || BN1 || J1-Z
|-
| A10 || L || Fast || BN2 || J1-BB
|-
| A13 || L || Fast || BP1 || J1-DD
|-
| A12 || L || Fast || BP2 || J1-FF
|-
| A15 || L || Fast || BR1 || J1-JJ
|-
| A14 || L || Fast || BR2 || J1-LL
|-
| A17 || L || Fast || BS1 || J1-NN
|-
| A16 || L || Fast || BS2 || J1-RR
|-
| C1 || L || Fast || BT2 || J1-TT
|-
| Ground || N/A || N/A || N/A || J1-VV
|-
| colspan="5" style="text-align:center;" | Header J2
|-
| D00 || L || Fast || AC1 || J2-B
|-
| D02 || L || Fast || AD1 || J2-D
|-
| D01 || L || Fast || AD2 || J2-F
|-
| D04 || L || Fast || AE1 || J2-J
|-
| D03 || L || Fast || AE2 || J2-L
|-
| D06 || L || Fast || AF1 || J2-N
|-
| D05 || L || Fast || AF2 || J2-R
|-
| D08 || L || Fast || AH1 || J2-T
|-
| D07 || L || Fast || AH2 || J2-V
|-
| D10 || L || Fast || AJ1 || J2-X
|-
| D09 || L || Fast || AJ2 || J2-Z
|-
| D12 || L || Fast || AK1 || J2-BB
|-
| D11 || L || Fast || AK2 || J2-DD
|-
| D14 || L || Fast || AL1 || J2-FF
|-
| D13 || L || Fast || AL2 || J2-JJ
|-
| PA || L || Fast || AM1 || J2-LL
|-
| D15 || L || Fast || AM2 || J2-NN
|-
| PB || L || Fast || AN2 || J2-RR
|-
| Ground || N/A || N/A || N/A || J2-TT
|-
| AC LO || L || Slow || BF1 || J2-VV
|-
| colspan="5" style="text-align:center;" | Header J3
|-
| NPR || L || Fast || AS2 || J3-B
|-
| NPG || H || Grant || AU1 || J3-D
|-
| BR7 || L || Fast || AT2 || J3-F
|-
| BG7 || H || Grant || AV1 || J3-J
|-
| BR6 || L || Fast || AU2 || J3-L
|-
| BG6 || H || Grant || BA1 || J3-N
|-
| BR5 || L || Fast || BC1 || J3-R
|-
| BG5 || H || Grant || BB1 || J3-T
|-
| BR4 || L || Fast || BD2 || J3-V
|-
| BG4 || H || Grant || BE2 || J3-X
|-
| INIT || L || Fast || AA1 || J3-Z
|-
| BBSY || L || Fast || AP2 || J3-BB
|-
| Ground || N/A || N/A || N/A || J3-DD
|-
| INTR || L || Fast || AB1 || J3-FF
|-
| SSYN || L || Fast || BU1 || J3-JJ
|-
| MSYN || L || Fast || BV1 || J3-LL
|-
| C0 || L || Fast || BU2 || J3-NN
|-
| Ground || N/A || N/A || N/A || J3-RR
|-
| SACK || L || Fast || AR2 || J3-TT
|-
| DC LO || L || Slow || BF2 || J3-VV
|}

[[Category: DEC Hardware]]

User:Jdl

2021-10-16T02:41:42Z

Jdl:

[[Image:Jay2.jpg|thumb|250px|left]]

<div style="font-size:150%; padding-bottom:10px">My name is Jay Logue</div>

I am a long-time software engineer and computer tinkerer with an interest in old computers
starting at the minicomputer era and going back to vaccum tubes and mechanical tabulators.

I am completely self-taught, having written my first program (in FORTRAN, on punched cards) at the age of 11.
Certain that computers were my destiny, I left highschool early to take a job writing software for Apple IIs and never looked back.
Since then I have worked as a software engineer/architect at many companies, most of which were start-ups,
some of which you may know (General Magic, WebTV, Microsoft, Nest, Google).

I am now retired.

My hobbies are very much constrained by the physical space I can devote to them, retro-computers included.
So for now I make do with an array of small PDP-11 and VAX systems, which I explore and repair, and generally
use to fritter away perfectly good electrons.

I have a few of small projects which I have contributed to the hobby. I hope to have more.

→ [https://github.com/jaylogue/retro-fuse retro-fuse]

→ [https://github.com/jaylogue/pdp-1105-console-usb-adapter PDP-11/05 console usb adapter]

→ [https://github.com/jaylogue/m9042-clone M9042 clone]

→ [https://github.com/jaylogue/dec-flip-chip-templates KiCAD templates for DEC FLIP CHIPS]

 

User:Jdl

2021-10-15T01:50:18Z

Jdl: Created page with " left <div style="font-size:150%; padding-bottom:10px">My name is Jay Logue</div> I am a long-time software engineer and computer tinkerer wit..."

File:Jay2.jpg

2021-10-15T00:46:26Z

Jdl: