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 Simple Large Computers 
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Joined: Mon Oct 07, 2019 2:41 am
Posts: 619
I am expanding a 20 bit design to 36 bits. You have unsigned characters (9) bits or word data (36) bits.
The rough draft for the 20 bit cpu is 16 opcodes, as 128 x 16 rom.


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Sun May 28, 2023 2:58 am

Joined: Mon Oct 07, 2019 2:41 am
Posts: 619
The rom's fit into 22v10's. Modified the microcode to use 16v8's for Alu I/O, rather than 22v10's.
MMu logic is still up in the air, but the 36 bit CPU looks to fit all on single mid sized PCB. 12" x 10"?
Ben.


Sun May 28, 2023 9:13 pm

Joined: Sat Feb 02, 2013 9:40 am
Posts: 2104
Location: Canada
Is this using late 70's technology?
Putting any expansion connectors on the board?

_________________
Robert Finch http://www.finitron.ca


Mon May 29, 2023 3:52 am WWW

Joined: Mon Oct 07, 2019 2:41 am
Posts: 619
More like the early 1980's. I am trying to squeze 3 1970's PCB's into 1 large PCB.
I have rethink the data path again, to get it to flow 8 bits per chip. The pal logic was designed
4 bits per chip using 4 bit wide bit slices.
Does any one make 9 bit bit wide memory
in thru the hole packaging?


Mon May 29, 2023 8:43 am

Joined: Sat Feb 02, 2013 9:40 am
Posts: 2104
Location: Canada
Quote:
Does any one make 9 bit bit wide memory
in thru the hole packaging?
Some of the old DRAM chips were 1 bit wide, so they could be combined with 4-bit wide chips to make 9 bits.
There might be a cache tag RAM that is 9 or 10 bits wide. But that is probably not early 80's tech.

_________________
Robert Finch http://www.finitron.ca


Tue May 30, 2023 7:40 am WWW

Joined: Mon Oct 07, 2019 2:41 am
Posts: 619
Take 5 min break, and I lose my draft.
The design will be similar to a IBM AT ( 6.6 Mhz) and 256kb of ram.
The computer will use 2 56 pin connectors per circut board, under each 16 bit alu.
A 4 bit 2901 will be in the middle. 8" x 11" pcb seems about right for now.
Two data sizes, byte (9 bits unsigned) and word 36 bits.
22v10's will emulate 74F823's and 74827's. (9 bit d f/f and 10 bit buffers).
Ben.


Tue May 30, 2023 7:53 am

Joined: Mon Oct 07, 2019 2:41 am
Posts: 619
This design is July xx 1984. Other than using CMOS chips, it seems buildable
(4 layer board may be needed for the large power draw) in that time frame. 22v10
's are must since bytes are 9 bits wide.
20 bits is segment size or 256K words of prgram space.
This first version will just have space for the MMU, but no logic to enable it.
Modern chips will replace the 64K x 1 drams used.
Ben.


Thu Jun 01, 2023 5:37 am

Joined: Mon Oct 07, 2019 2:41 am
Posts: 619
Code:
1981 computer with 9 bits per byte - 36 bit bus
6.66 mhz makes use of 9 bit wide buffers and flip flops.
16 page mmu 512kb segments/ 64k drams

   36 bit version 2 meg memory (MAX)
                         256kb memory

    9    8    7    6    5    4    3    2    1
  +----+----+----+----+----+----+----+----+----+
  |COOO:mAAA:aXXX:SS+#:####:####:####:####:####|
  +----+----+----+----+----+----+----+----+----+

 A X     OP      CC       
 0 # Z     ST/SN   -       
 1 S S     XOR     Z                 
 2 X X     OR      S
 3 Y Y     AND     Z+S     
 4 A A     LD/LN   !C   
 5 B B     CAD/CAC !(C+Z)
 6 C C     SUB/SBC T
 7 D D     ADD/ADC T

     SN,LN NO MAP
     SS 00 word
        01 byte signed
        10 half unigned
        11 half signed


Post note, Memory is still to complex with all this byte shifting.
1 st version no mmu 0x0(6/7)0000 maps to 0x1(E/F)0000
ss 00 word
ss 01 byte unsigned
ss 1x reserved


Sat Jun 03, 2023 6:54 pm

Joined: Mon Oct 07, 2019 2:41 am
Posts: 619
Really cutting back on the design hardware wise. Gone to a core style memory cycle.
Using 1988 tech to give me a 1968 design. Front panel now just POWER,run and stop.
PDP 8/e speed .6 us clock cycle, 1.2 us memory cycle. Just word addressing,18 bits mar,
36 bit bus.
Ben.


Thu Jun 08, 2023 7:26 pm

Joined: Mon Oct 07, 2019 2:41 am
Posts: 619
Looking for cheap front panel swiches that I can mount on a pcb.
I need 36+ switches, and footprints. Any recomendations. Micro slide
switches are too small. I am also looking for a LED indicator that has the
led, dropping resistor and driver all in the same package.


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Fri Jun 09, 2023 4:35 am

Joined: Mon Oct 07, 2019 2:41 am
Posts: 619
Code:
*
   JUNE 9 2023 draft
   36 bit CPU  Ben 67 / 1988 version
   No bytes 4.77 MHZ 1.25 US
   CORE timing LIMITED front panel

    9    8    7    6    5    1    3    2    1
  +----+----+----+----+----+----+----+----+----+
  |COOO:AAAA:XXXX:MAY+:####:####:####:####:####|
  +----+----+----+----+----+----+----+----+----+

       A        OP      CC       
     0 Z  A     ST      -       
    1 S  B     XOR     Z                 
    2 T  C     OR      S
    3 U  D     AND     Z+S     
    1 V  E     LD      !C   
    5 W  F     CAD/CAC !(C+Z)
     6 X  G     SUB/SBC T
     7 Y  H     ADD/ADC T
   

  '/'     LRDE COMMENT
  '*'     BLOCK COMMENT  BEGIN/END  ONLY
  #OOO    OCTAL PROGRAM COUNTER
      TOKENS
      PROM A    PRB#
      tst 0001    0
      ctl 0001    0
      y   0002    1
      wrd 000C   
      sx  0004    2  +- 20 bits
      1   0008    3
      op  2000    5'
      ld  0020    5
      sub 2020
      no  0040    6
      sft 0080    7

      PROM B    PRB#

      by  0100    0' not used
      IR  0800    3'   
      rd  0010    1
      wr  0210    1'
      pc  0000
      ac  0040    3
      ix  2000    5'
      RD  1000    1'
      sp  8000    7'
      ax  2040
   
    REAL SIMPLE CPU
   (J-PAN_,ST_)(JMP_,M,A)(cnt)
     0  ST_  JMP_,M A NORMAL
     1  X    PAN_ X X TRAP
     1  X    PAN_ X X PANEL
  *

 
   #000        / CTL
    PC Y 1      RD
    IX CTL NO   IR
    PC          RD
    PC 1        IR

    #010    /   JSV # 
            /         
         
    SP 1 SUB    WR RD
    PC 1 SUB    WR
    PC LD SX    RD
    PC 1        IR

    #020    /   JMP X
    IX NO SX    RD
    PC          IN
    PC LD WRD   RD
    PC 1        IR

    #030    /   JMP A+-
    IX Y SX     RD
    PC          IN
    PC LD WRD   RD
    PC 1        IR

    #040    /   LEA MA 00

    PC Y 1      RD
    AX SX       IR
    PC          RD
    PC 1        IR

    #050    /   LEA MA 01

    PC Y 1      RD
    AX SX       IR
    PC          RD
    PC 1        IR

 

    #060    /   ST X
    AX NO SX    WR  RD
    AC          WR
    PC          RD
    PC 1        IR

    #070    /   ST A+-
    IX Y SX     WR  RD
    AC          WR
    PC          RD
    PC 1        IR

    #100    /   BCC #
    IX TST     
    PC           RD   
    PC  1        IR
    PC
    / TRUE
    PC LD SX    RD
    PC 1        IR

    #110    /   SCC
    IX TST
    PC  1 Y     RD   
    IX LD 0     IR
    PC
    / TRUE
    PC 1  Y      RD
    IX LD SX    IR
 
    #120    / SHIFT X 6
    IX SFT
    IX SFT
    IX SFT
    IX SFT
    IX SFT
    PC 1  Y    RD
    IX SFT     IR

    #130    / SHIFT
    PC 1  Y    RD
    IX  SFT    IR

    #140    /   MEM %   
    PC 1 Y      RD
    AX OP       IR

    #150    /   MEM #     
    PC 1 Y      RD
    AC OP SX    IR

    #160    /   MEM X
    AX NO SX    RD
    PC          IN
    PC 1 Y      RD
    AC OP WRD   IR

    #170    /   MEM A+
    IX SX Y     RD
    PC          IN
    PC 1  Y     RD
    AC OP WRD   IR
 
    / TRAP DON'T CARE IR RDPUT
    / PUSH (PC-1), P=1

    #240        / TRAP
    SP 1 SUB    WR RD
    PC 1 SUB    WR
    PC LD 1     RD
    PC 1        IR

    #340        / TRAP
    SP 1 SUB    WR RD
    PC 1 SUB    WR
    PC LD 1     RD
    PC 1        IR

    #250        / TRAP
    SP 1 SUB    WR RD
    PC 1 SUB    WR
    PC LD 1     RD
    PC 1        IR

    #350        / TRAP
    SP 1 SUB    WR RD
    PC 1 SUB    WR
    PC LD 1     RD
    PC 1        IR

    #260        / TRAP
    SP 1 SUB    WR RD
    PC 1 SUB WR
    PC LD 1     RD
    PC 1        IR

    #360        / TRAP
    SP 1 SUB    WR RD
    PC 1 SUB WR
    PC LD 1     RD
    PC 1        IR

    #270        / TRAP
    SP 1 SUB    WR RD
    PC 1 SUB WR
    PC LD 1     RD
    PC 1        IR

    #370        / TRAP
    SP 1 SUB    WR RD
    PC 1 SUB WR
    PC LD 1     RD
    PC 1        IR


    // PANEL
    #200        / IDLE
     PC
     PC
     PC
     PC         IR

    #300        / IDLE
     PC
     PC
     PC
     PC         IR

    // PANEL
    #210        / ALD
     PC NO LD OP RD
     PC          IN
     PC LD WRD
     PC         IR

    #310        / ALD
     PC NO LD OP RD
     PC          IN
     PC LD WRD
     PC          IR

    #220        / EXAM
     PC 1 Y     RD     
     PC         IN
     PC   
     PC         IR

    #330        / EXAM
     PC 1 Y     RD
     PC         IN
     PC
     PC         IR

    #230        / DEP
     PC NO LD OP RD
     PC          IN
     PC 1 Y      WR RD   
     PC LD NO WRD WR IR
 

    #330        / DEP
     PC NO LD OP RD
     PC          IN
     PC 1 Y      WR RD
     PC LD NO WRD WR IR
  *
  FILES and chips

   "JTRAP" irq and counter 1
   "JALU"  alu decode      2 
   "JCON"  control logic   3
   "JMEM"  memory logic    4
   "JMLX"  a,b reg logic   5
   "JMX?"  1,2,3 input mulx 9 wide 6 7 8
   "JROMA" pal - prom a 9
   "JROMB" pal - prom b 10
   74act14 x 1  inverter 11
   74act00 x 1  nand     12
   74act823 x 2 ir reg   13 14
   74act823 x 4 in reg   15 16 17 18
   74act823 x 4 out reg  19 20 21 22
   2901C x 1    4 bit slice  23
   7C9101 x 2   16 bit slice 24 25
 
   *
 // ALL DONE
 


A Cmos computer, with 25 chips for the main board ( alu and control logic ).
Power down from 8 amps to 1 amp. Simple front panel, but no blinky lights.
Having 9 bit wide registers and buffers is so nice.

Ben.


Sat Jun 10, 2023 4:18 am

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1789
Nice - do you plan to build it?


Sat Jun 10, 2023 6:45 am

Joined: Mon Oct 07, 2019 2:41 am
Posts: 619
BigEd wrote:
Nice - do you plan to build it?

I do plan to build it, at some point.
At the moment am gathering collecting parts, mostly from ebay.
It is the mechanical parts like switches and leds and
connectors that need to played with now for the mother board
and front panel layout.
I am also in need of a good schematic capture and PCB lay out program
that is Imperal not metric in layouts and footprints. I guess I got about
1500 pins per pcb at 8" x 11". I have budget of about $500 Canadian
for that.
Mechanical construction is my weak point, as all I have the kitchen table
and a good soldering iron, and a old drill.

Ben.


Sat Jun 10, 2023 8:10 am

Joined: Sat Feb 02, 2013 9:40 am
Posts: 2104
Location: Canada
Quote:
I am also in need of a good schematic capture and PCB lay out program
that is Imperal not metric in layouts and footprints. I guess I got about
Have you had a look at KiCAD? I believe it supports either set of measurements.

_________________
Robert Finch http://www.finitron.ca


Sun Jun 11, 2023 11:29 am WWW

Joined: Mon Oct 07, 2019 2:41 am
Posts: 619
Kicad seems still have a footprint problem, and is meteric based.
What it I want to use .156 inch spacing connectors, and card edge connectors, or Yang Foo switchs.
If sombody came up with a standard library for items like that it would consider it a valid option.
Often I want to design a schematic segment, and leave detals like footprints for later.
What if part XYX needs a footprint changed later on the PCB lay out. A 7475 vs 74275.
I want to start drawing schematics, not makeing components for incomplete libraries, since version #1.
This includes old TTL, and other logic, not some new transistor with 5000 lay out patterns,
Can kicad import net lists?
Can I have design template, so I can start a PCB with the BASIC power and ground and finger
routing all done, like a S100 card with fingers and voltage regulators.
I want good manual routing, not flaky auto routing.
Ben.
PS: I also want a game pad as input device for schematic layout.
(RS) X to kill that logic bug. :)
To me it makes sense, as game pad has ample buttons for layout, not ALT SHIFT RIGHT FUNCTION 742 to end a line.
PPS: I dislike Kicad, for the simple reason they keep revising to a new version every other
year, and libraries keep changing. I sill have a few .156 card edge connectors, Yang FOO switches
and plan to use fingers on the PCB.


Sun Jun 11, 2023 4:13 pm
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