[Simh] PDP-8 and OS/8 assembly

[Bill Cunningham]

  ----- Original Message ----- 
  From: Ethan Dicks 
  To: simh at trailing-edge.com 
  Sent: Sunday, June 25, 2017 6:22 PM
  Subject: Re: [Simh] PDP-8 and OS/8 assembly


  On Sun, Jun 25, 2017 at 5:50 PM, Bill Cunningham <billcun at suddenlink.net> wrote:
  >     I am reading a bit about the machine the PDP-8. 4K fortran I guess was
  > used,

  That was one option, yes.

  > there were 8 "registers" if that's right.

  Not sure where this is coming from...

  Oh I'm sorry I meant operation codes. 3 registers. I believe 8 opcodes.

  There's the 12-bit Accumulator and its associated LINK (carry) bit.
  Some models always have a 12-bit MQ (Multiplier Quotient) register,
  some get an MQ when the EAE is installed, and some never get it.
  There's a 12-bit Program Counter, and two extended field registers,
  either 1-bit, 2-bit (PDP-8/L) or 3-bit (many other models) if the
  memory extension hardware is installed (required to have over 4K)

  > And 12 bit words.

  Yes.

  > As far as languages here, is Macro-8 assembly language?

  Look for assemblers called PAL (PAL III and PAL8) and MACREL (though
  MACREL was a late addition)

  OK

  >     Is there an assembler available for PDP-8? OS/8 preferrably but tss-8 or
  > anything would do?

  Plenty of assembler possibilities with OS/8.  I have no experience with TSS-8.

  http://www.computinghistory.org.uk/det/8391/PDP8-PALAssembly-Language/

  -ethan

  OK I see. The registers other than AC and the two others are all I've heard of. Where Do I ge this...

  https://www.grc.com/pdp-8/pdp-8.htm

  Pretty nice page. I just found it earlier.

  Bill
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