Difference between revisions of "M9312 ROM"
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The '''M9312 [[Read-only memory|ROM]]''' card was a [[UNIBUS]] card for the [[PDP-11]] series of computers. It contained 512 words of [[Read-only memory|ROM]] memory, all readable directly from the UNIBUS (i.e. not windowed). The M9312 also provided [[termination]] for the UNIBUS. | The '''M9312 [[Read-only memory|ROM]]''' card was a [[UNIBUS]] card for the [[PDP-11]] series of computers. It contained 512 words of [[Read-only memory|ROM]] memory, all readable directly from the UNIBUS (i.e. not windowed). The M9312 also provided [[termination]] for the UNIBUS. | ||
| − | It was a [[DEC card form factor|dual]] format card, intended for use in the | + | It was a [[DEC card form factor|dual]] format card, intended for use in the [[DEC edge connector contact identification|two top (AB) sections]] of a [[Modified UNIBUS Device|MUD]] slot, or in a UNIBUS in/out slot. |
The board occupied addresses 773000-773776 (high ROM) and 765000-765776 (low ROM); a configuration jumper allowed the lower block to be disabled. | The board occupied addresses 773000-773776 (high ROM) and 765000-765776 (low ROM); a configuration jumper allowed the lower block to be disabled. | ||
Revision as of 01:00, 17 December 2017
The M9312 ROM card was a UNIBUS card for the PDP-11 series of computers. It contained 512 words of ROM memory, all readable directly from the UNIBUS (i.e. not windowed). The M9312 also provided termination for the UNIBUS.
It was a dual format card, intended for use in the two top (AB) sections of a MUD slot, or in a UNIBUS in/out slot.
The board occupied addresses 773000-773776 (high ROM) and 765000-765776 (low ROM); a configuration jumper allowed the lower block to be disabled.
Contents
ROMs
The contents of the standard PROMs from DEC provided a console emulator, basic CPU and main memory diagnostics, and the ability to bootstrap the machine from disk, magnetic tape, etc; however, the board could be used for any purpose.
The board used five 4-bit wide PROMs to hold the data; the DEC-supplied pre-programmed PROMs included the console emulator and diagnostics in one ROM, and the other four to hold the selected bootstraps (selected from a large set available from DEC, see below).
The diagnostics include i) primary CPU tests, ii) secondary CPU tests, and a memory test. The primary tests are performed before entering the console emulator; if a failure is detected, the processor goes into an infinite loop at the failing test. The secondary tests and memory test are run when a boot command is given from the console emulator.
There were two different emulator/diagnostic PROMs; one for the PDP-11/70 and PDP-11/60, which check the machine's cache, and one for all the other PDP-11 models.
Configuration
The board was configured using both a single 10-switch DIP switch, S1, and a number of jumpers, together with they control the board's behaviour.
Switches
Configuration switches control which address the CPU jumps to on power on.
A clever kludge, controlled by one configuration switch, allowed the board to force the CPU to read its power-on PC and PS from the ROM, at a location set by other configuration switches, thereby allowing auto-boot on power-on. If S1-1 is set to 'off' (open), the new PS and PC loaded on power-on will point to the high ROM; if 'on' (closed), it will be in the low ROM.
If S1-2 is 'off', the system will power-up normally; if 'on', the CPU will obtain its new PC/PS pair from locations 173024 on the card, which contain a mixture of bits from the ROM (high bits) and the configuration switches (low bits), which can be used to force the CPU to start executing in the ROM on power-on.
Switches S1-3 through S1-10 contain bits 8 through 1 of the power-on PC (above).
Jumpers
- W1-W5 - When inserted, termination is provided for the bus grant lines of the UNIBUS.
- W6 - In for machines with push-button boot capability
- W7 - Always in
- W8 - When inserted, the low bank of memory on the card (765000-765777) is disabled; when removed, it is enabled.
- W9-W10 - Out for use with a PDP-11/60; in for all others
- W11-W12 - In for use with a PDP-11/60; out for all others
Connector tabs
The board contains four connector tabs, which may be used with a pair of external switches, to control the board's behaviour.
Two, TP2 and TP3, are ground returns (for TP1 and TP4, respectively). TP1, when momemtarily grounded, forces the machine to execute a power-fail/restart sequence (by asserting UNIBUS line ACLO). TP4, when grounded, forces the machine to execute the on-board ROM on power on, no matter what the position of S1-2 (above).
PROM variants
The following table lists the DEC standard PROMs by part number, and the devices (and device code) they support. When a particular PROM suppports more than one type of device, the second device type is indicated with a '*' after the part number.
| ROM part # | Device | Controller | Device Code |
|---|---|---|---|
| 23-751A9 | RL01/RL02 disk | RL11 | DL |
| 23-752A9 | RK06/RK07 disk | RK611 | DM |
| 23-753A9 | RX01 floppy | RX11 | DX |
| 23-811A9 | RX02 floppy | RX211 | DY |
| 23-755A9 | RP02/RP03 disk | RP11 | DP |
| 23-755A9* | RP04/RP05/RP06, RM02/RM03 disk | RH11, RH70 | DB |
| 23-756A9 | RK03/RK05 disk | RK11 | DK |
| 23-756A9* | TU55/TU56 DECtape | TC11 | DT |
| 23-757A9 | TU16/TE16 magtape | TM02, TM03 | MM |
| 23-758A9 | TU10/TE10/TS03 magtape | TM11 | MT |
| 23-759A9 | RS03/RS04 fixed disk | RH11, RH70 | DS |
| 23-760A9 | PC05 high-speed reader | PC11 | PR |
| 23-760A9* | console low-speed reader | DL11 | TT |
| 23-761A9 | TU60 DECcassette | TA11 | CT |
| 23-762A9 | RS11 fixed disk | RF11 | RS |
| 23-762A9* | RS64 fixed disk | RC11 | RS |
| 23-763A9 | card reader | CR11 | CR |
| 23-764A9 | TS04, TU80 magtape | TS11, TU80K | MS |
| 23-765A9 | TU58 DECtapeII | DL11 | DD |
See also
External links
Reference
- EK-M9312-TM-003, M9312 bootstrap/terminator module technical manual
