Difference between revisions of "Talk:Microcode"
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| − | 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 | + | 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) |
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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) | ||
Revision as of 16:16, 13 May 2021
Another meaning
So the 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 similar concept; not sure if it uses the same term (I'll check) 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. INSTRUCTION MANUAL - EAE - KE09A Section 1.1. Jnc (talk) 16:15, 13 May 2021 (CEST)
