Floating device address space - Revision history

Jnc: probable explanation for base units

2023-02-08T13:44:49Z

probable explanation for base units

← Older revision		Revision as of 13:44, 8 February 2023
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	\| 30 \|\| [[TU81 magtape drive\|TU81]] \|\| 04 \|\| Only extra		\| 30 \|\| [[TU81 magtape drive\|TU81]] \|\| 04 \|\| Only extra
	\|}		\|}

			It will be noticed that the types with an 'extra unit' annotation are all [[mass storage]] devices, generally [[disk]]s. This probably means that the 'base' unit is assigned a fixed address, so that [[bootstrap]]s do not have to contain the lengthy algorithm to deal with floating addresses in order to boot from them.

	==See also==		==See also==

Jnc: Link board

2023-02-08T03:02:34Z

Link board

← Older revision		Revision as of 03:02, 8 February 2023
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	\| 28 \|\| KMS11 \|\| 20		\| 28 \|\| KMS11 \|\| 20
	\|-		\|-
	\| 29 \|\| VS100 \|\| 20		\| 29 \|\| [[VS100]] \|\| 20
	\|-		\|-
	\| 30 \|\| [[TU81 magtape drive\|TU81]] \|\| 04 \|\| Only extra		\| 30 \|\| [[TU81 magtape drive\|TU81]] \|\| 04 \|\| Only extra

Jnc: add a bunch of devices from a later version

2022-08-30T01:59:05Z

add a bunch of devices from a later version

@@ Line 56: / Line 56: @@
 | 23 || [[ISB11]] || 010
 |-
-| 23 || [[DMV11 Synchronous Controller|DMV11]] || 020
+| 24 || [[DMV11 Synchronous Controller|DMV11]] || 020
 |}

Jnc: /* Further reading */ +PDP-11 Architecture Handbook

2022-08-30T01:17:42Z

Further reading: +PDP-11 Architecture Handbook

← Older revision		Revision as of 01:17, 30 August 2022
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	* [[Floating device vectors]]		* [[Floating device vectors]]

			==Further reading==

			* ''PDP-11 Architecture Handbook'' (not online); 'Floating CSR Address Devices', in Appendix A

	==External links==		==External links==

Jnc: /* External links */ dates on cover

2022-08-29T20:27:25Z

External links: dates on cover

← Older revision		Revision as of 20:27, 29 August 2022
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	==External links==		==External links==

	* [http://www.bitsavers.org/pdf/dec/handbooks/EB-20443-20_Peripherals_Handbook_1981.pdf peripherals handbook (1981)] - Appendix D, 'Floating CSR Address Devices' (pg. 494 of the PDF]		* [http://www.bitsavers.org/pdf/dec/handbooks/EB-20443-20_Peripherals_Handbook_1981.pdf peripherals handbook (1981-82)] - Appendix D, 'Floating CSR Address Devices' (pg. 494 of the PDF]

	[[Category: UNIBUS]]		[[Category: UNIBUS]]
	[[Category: QBUS]]		[[Category: QBUS]]

Jnc: /* External links */ +peripherals handbook (1981)

2022-08-29T19:22:30Z

External links: +peripherals handbook (1981)

← Older revision		Revision as of 19:22, 29 August 2022
Line 62:		Line 62:

	* [[Floating device vectors]]		* [[Floating device vectors]]

			==External links==

			* [http://www.bitsavers.org/pdf/dec/handbooks/EB-20443-20_Peripherals_Handbook_1981.pdf peripherals handbook (1981)] - Appendix D, 'Floating CSR Address Devices' (pg. 494 of the PDF]

	[[Category: UNIBUS]]		[[Category: UNIBUS]]
	[[Category: QBUS]]		[[Category: QBUS]]

Jnc: a few later addns

2021-08-25T18:39:11Z

a few later addns

← Older revision		Revision as of 18:39, 25 August 2021
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	\|-		\|-
	\| 20 \|\| [[DR11-B parallel interface\|DR11-B]] \|\| 010 \|\| After second		\| 20 \|\| [[DR11-B parallel interface\|DR11-B]] \|\| 010 \|\| After second
			\|-
			\| 21 \|\| [[DMP11]] \|\| 010
			\|-
			\| 22 \|\| [[DPV11]] \|\| 010
			\|-
			\| 23 \|\| [[ISB11]] \|\| 010
			\|-
			\| 23 \|\| [[DMV11 Synchronous Controller\|DMV11]] \|\| 020
	\|}		\|}

Jnc: Avoid redir

2021-08-01T23:49:25Z

Avoid redir

← Older revision		Revision as of 23:49, 1 August 2021
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	\| 3 \|\| [[DQ11]] \|\| 010		\| 3 \|\| [[DQ11]] \|\| 010
	\|-		\|-
	\| 4 \|\| [[DU11]] \|\| 010		\| 4 \|\| [[DU11 synchronous serial line interface\|DU11]] \|\| 010
	\|-		\|-
	\| 5 \|\| [[DUP11 synchronous serial line interface\|DUP11]] \|\| 010		\| 5 \|\| [[DUP11 synchronous serial line interface\|DUP11]] \|\| 010

Jnc: Mostly there

2021-07-27T18:20:32Z

Mostly there

New page

The '''floating device address space''' is a block of [[address space]] in the I/O page of the [[UNIBUS]] (and later the [[QBUS]]) used to hold the control [[register]]s of [[peripheral]]s. Originally, each specific peripheral was assigned a fixed address for its registers; once the number of different device types became large, circa 1975, this was no longer feasible (or scalable), and the 'floating' approach was adopted instead.

In this, a block of address space (on the UNIBUS, from 0760010 to 0763776) is allocated for 'floating' devices. Within that block, devices are assigned in a fixed order, with all the devices of any type in a contiguous group. There is an empty minimum-sized group for each type of which there are no devices of that type present, and a gap between each group of devices (to mark the end of each group). (Each actual group must start on an address of the required modulus; e.g. if there is one DJ11 and one DH11, the DJ11 would be at 0760010, the 'end of DJ11s gap' would be at 0760020, the DH11 could not be at 0760030, but would have to be at 0760040.)

Floating devices, in assignment order:

{| class="wikitable"
! Rank !! Device !! Size<BR>(modulus) !! Comment
|-
| 1 || [[DJ11 asynchronous serial line interface|DJ11]] || 010
|-
| 2 || [[DH11 asynchronous serial line interface|DH11]] || 020
|-
| 3 || [[DQ11]] || 010
|-
| 4 || [[DU11]] || 010
|-
| 5 || [[DUP11 synchronous serial line interface|DUP11]] || 010
|-
| 6 || [[LK11]] || 010
|-
| 7A || [[DMC11]] || 010
|-
| 7B || [[DMR11]] || 010
|-
| 8 || [[DZ11 asynchronous serial line interface|DZ11]] || 010
|-
| 9 || [[KMC11]] || 010
|-
| 10 || [[LPP11]] || 010
|-
| 11 || VMV21 || 010
|-
| 12 || VMV31 || 020
|-
| 13 || [[DWR70]] || 010
|-
| 14 || [[RL11 disk controller|RL11]] || 010 || Only extra
|-
| 15 || [[LPA11]] || 020 || Only extra
|-
| 16 || [[KW11-C]] || 010
|-
| 17 || Reserved || 010
|-
| 18 || [[RX11 floppy disk controller|RX11]] || 010 || Only extra
|-
| 19 || [[DR11-W]] || 010
|-
| 20 || [[DR11-B parallel interface|DR11-B]] || 010 || After second
|}

==See also==

* [[Floating device vectors]]

[[Category: UNIBUS]]
[[Category: QBUS]]