Talk:Microcode - Revision history

Jnc: Yes, quite natural

2021-05-15T12:29:33Z

Yes, quite natural

Larsbrinkhoff: /* Another meaning */

2021-05-15T07:52:43Z

‎Another meaning

Jnc: /* Another meaning */ common DEC jargon

2021-05-13T14:16:03Z

‎Another meaning: common DEC jargon

Jnc: /* Another meaning */

2021-05-12T07:14:58Z

‎Another meaning

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==Another meaning==

So the [http://www.bitsavers.org/pdf/dec/pdp4/F-41D_PDP4brochure_Sep63.pdf PDP-4 brochure] contains what seems to be another meaning for "microcode". It say (pg. 3, in 'Extended Arithmetic Element') "adds 23 micro coded instructions". I'm pretty sure this isn't 'microcode' in the modern sense (the [[PDP-9]] was the first microcoded DEC machine), but it means instructions where there were a number of bits, each of which controlled an independent operation (e.g. 'clear link (carry) bit'), and can be set in any combination. The [[PDP-8 family]] has a [[PDP-8 architecture#Group 1 "operate" instruction operations|similar concept]]; not sure if it uses the same term (I'll check) [[User:Jnc|Jnc]] ([[User talk:Jnc|talk]]) 09:14, 12 May 2021 (CEST)

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	: I always thought this quite natural in the sense that individual bits control specific functions independently of other bits in the "microcode" field. [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 09:52, 15 May 2021 (CEST)		: I always thought this quite natural in the sense that individual bits control specific functions independently of other bits in the "microcode" field. [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 09:52, 15 May 2021 (CEST)
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		+	: Oh, I agree; it is a quite natural 'extension' of the term. But it is a different meaning. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 14:29, 15 May 2021 (CEST)

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	This seems to have been common DEC jargon; the PDP-8 does indeed use it, and also see e.g. [http://www.bitsavers.org/pdf/dec/pdp9/DEC-09-I2AA-D_KE09A_Feb69.pdf INSTRUCTION MANUAL - EAE - KE09A] Section 1.1. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 16:15, 13 May 2021 (CEST)		This seems to have been common DEC jargon; the PDP-8 does indeed use it, and also see e.g. [http://www.bitsavers.org/pdf/dec/pdp9/DEC-09-I2AA-D_KE09A_Feb69.pdf INSTRUCTION MANUAL - EAE - KE09A] Section 1.1. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 16:15, 13 May 2021 (CEST)
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		+	: I always thought this quite natural in the sense that individual bits control specific functions independently of other bits in the "microcode" field. [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 09:52, 15 May 2021 (CEST)

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	==Another meaning==		==Another meaning==

−	So the [http://www.bitsavers.org/pdf/dec/pdp4/F-41D_PDP4brochure_Sep63.pdf PDP-4 brochure] contains what seems to be another meaning for "microcode". It ~~say~~ (pg. 3, in 'Extended Arithmetic Element') "adds 23 micro coded instructions". I'm pretty sure this isn't 'microcode' in the modern sense (the [[PDP-9]] was the first microcoded DEC machine), but it means instructions where there were a number of bits, each of which controlled an independent operation (e.g. 'clear link (carry) bit'), and can be set in any combination. The [[PDP-8 family]] has a [[PDP-8 architecture#Group 1 "operate" instruction operations\|similar concept]]; not sure if it uses the same term (I'll check) [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 09:14, 12 May 2021 (CEST)	+	So the [http://www.bitsavers.org/pdf/dec/pdp4/F-41D_PDP4brochure_Sep63.pdf PDP-4 brochure] contains what seems to be another meaning for "microcode". It says (pg. 3, in 'Extended Arithmetic Element') "adds 23 micro coded instructions". I'm pretty sure this isn't 'microcode' in the modern sense (the [[PDP-9]] was the first microcoded DEC machine), but it means instructions where there were a number of bits, each of which controlled an independent operation (e.g. 'clear link (carry) bit'), and can be set in any combination. The [[PDP-8 family]] has a [[PDP-8 architecture#Group 1 "operate" instruction operations\|similar concept]]; not sure if it uses the same term (I'll check) [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 09:14, 12 May 2021 (CEST)
		+
		+	This seems to have been common DEC jargon; the PDP-8 does indeed use it, and also see e.g. [http://www.bitsavers.org/pdf/dec/pdp9/DEC-09-I2AA-D_KE09A_Feb69.pdf INSTRUCTION MANUAL - EAE - KE09A] Section 1.1. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 16:15, 13 May 2021 (CEST)