Page 1 of 3

ZX81 Chip Pin-outs

Posted: Sun Nov 24, 2013 11:23 am
by 1024MAK
ZX81 Chip Pin-outs


Note the notch cut-out at the top of the chip. Pin 1 can also be designated by a white dot marked next to it.
Z80 CPU in DIL 40 pin plastic package showing pin numbering
Z80 CPU in DIL 40 pin plastic package showing pin numbering
Z80 CPU
Z80 CPU
Z80 CPU pin-out.png (80.93 KiB) Viewed 8327 times
ZX81 ULA
ZX81 ULA
ZX81 ULA.png (37.55 KiB) Viewed 7863 times
D2364C ROM
D2364C ROM
D2364C ROM.png (29.92 KiB) Viewed 8327 times

Re: ZX81 Chip Pin-outs

Posted: Sun Nov 24, 2013 11:23 am
by 1024MAK
RAM
2114 SRAM
2114 SRAM
2114 SRAM pin-out.png (21.7 KiB) Viewed 8328 times
MK4118A & MK4801A 1K SRAM
MK4118A & MK4801A 1K SRAM
MK4118A & MK4801A SRAM.png (50.96 KiB) Viewed 8328 times
IMG_4191.JPG
NEC uPD4016 2K SRAM
(176.07 KiB) Downloaded 1382 times
2016, 6116, 2k SRAM
2016, 6116, 2k SRAM
2016, 6116, 2k SRAM pin-out.png (26.22 KiB) Viewed 6880 times
MK4816 Pseudostatic 2K RAM
MK4816 Pseudostatic 2K RAM
MK4816 Pseudostatic RAM.png (82 KiB) Viewed 8328 times
62256 32k SRAM
62256 32k SRAM
62256 32k SRAM pin-out.png (50.97 KiB) Viewed 6879 times
Mark

Re: ZX81 Chip Pin-outs

Posted: Sun Nov 24, 2013 11:32 am
by 1024MAK
Sinclair ZX81 ULA

Code: Select all

ZX81 Ferranti ULA
Pin  Function  Function  Pin
 1   A7'         +5V     40
 2   A8'         A6'     39
 3   A2'         A5'     38
 4   A1'         A4'     37
 5   A0'         A3'     36
 6   /RD         OSC     35
 7   /IORQ       GND     34
 8   /WR         KBD0    33
 9   /MREQ       D0      32
10   /M1         KBD1    31
11   A14         D1      30
12   /RAMCS      KBD2    29
13   /ROMCS      D2      28
14   /CLK (CPU)  KBD3    27
15   /NMI        D3      26
16   TV/TAPE     KBD4    25
17   /HALT       D4      24
18   A15         D5      23
19   D7          USA/UK  22
20   TAPE IN     D6      21
I hope these pin-outs are helpful to those who do not yet have this information etched in to their minds yet :mrgreen:
If you spot any errors, please let me know so that I can correct them.
Also note that the ROM socket and RAM socket may be bigger than the size of the chip actually fitted. These pin-outs are for the chips, not the sockets.

1 bit X 16k 4116 DRAM
As used in both Sinclair's 16k byte RAM pack and many other 16k byte RAM expansions.
4116 DRAM pin-out
4116 DRAM pin-out
4116 DRAM pin-out_p.png (35.44 KiB) Viewed 7099 times
4116 DRAM voltages and currents
4116 DRAM voltages and currents
4116 current_p.png (21.25 KiB) Viewed 7099 times
Mark

Re: ZX81 Chip Pin-outs

Posted: Sun Nov 24, 2013 4:11 pm
by Rink
Never come across PSRAM before - looks cool. Anyone know where you can buy it?

I hate DRAM, but find the capacities of SRAM to be quite disappointing so this stuff looks interesting.

Re: ZX81 Chip Pin-outs

Posted: Sun Nov 24, 2013 10:24 pm
by sirmorris
Great stuff, Mark! Thanks :D

Re: ZX81 Chip Pin-outs

Posted: Sun Nov 24, 2013 10:43 pm
by yalokinh
Great, thanks

Re: ZX81 Chip Pin-outs

Posted: Wed Nov 27, 2013 4:48 pm
by yalokinh
For the 2114, i think there are two of them, do the pins for both chips go to the same place?

Re: ZX81 Chip Pin-outs

Posted: Wed Nov 27, 2013 4:58 pm
by PokeMon
As for the RAMs the address lines and data lines can be swapped in any way, you can not trust that A5 goes to A5 or that I/O3 goes to D3 or D4.

Re: ZX81 Chip Pin-outs

Posted: Wed Nov 27, 2013 6:34 pm
by 1024MAK
yalokinh wrote:For the 2114, i think there are two of them, do the pins for both chips go to the same place?
If you are using 2114 SRAM chips, two are needed. One does 4 bits of the 8 bit byte, the other does the remaining 4 bits of the byte. Connect the ten address lines of both to the A0 - A9 address lines of the Z80 CPU.

As PokeMon says, the actual order of the connections is not important. What do we mean by this? Well, as the Z80 writes data to the RAM , and the RAM does not care where that data is stored, it makes no difference if the address lines are mixed up. For example you can route Z80 CPU A0 to RAM A2, CPU A1 to RAM A1, CPU A3 to RAM A0, CPU A4 to RAM A3 etc. as long as all the address lines connect to the "lower" address lines (A0 - A9) of the CPU.

You can do the same for the data lines (CPU D0 - D7) to the RAM I/O1 - I/O4. Route four of the data lines (CPU D0 - D7) to the I/O pins of one 2114, and route the remaining data lines to the second 2114 chip :mrgreen:

Note that the ULA named pins do have to tie up with ("connect with" either directly or via the resistors) the similar named Z80 CPU pins as per the schematic diagram.

The system will work fine, as the CPU can read and write data to the RAM.

Note this mixed up connection system will not work for the ROM. It only works for static RAM chips.

Mark

Edited to add a word that I missed out (work) in the last sentence :oops:

Re: ZX81 Chip Pin-outs

Posted: Thu Nov 28, 2013 2:35 am
by yalokinh
ah cool, learning lots!
Thanks