Search found 443 matches

by Nasta
Sun Sep 19, 2021 5:22 pm
Forum: Hardware
Topic: New Sockets For Old
Replies: 4
Views: 1448

Re: New Sockets For Old

There are 48 pin turned pin sockets and I would recommend those every time you need to replace a socket. Color certainly does not matter, I think the latest issued Samsung made machines had CPU sockets similar to the ULA and IPC sockets.
by Nasta
Fri Sep 17, 2021 6:16 pm
Forum: Hardware
Topic: DIY keyboard
Replies: 25
Views: 6041

Re: DIY keyboard

No. All keys must be wired between one row and one column line. But, there are keys that have double switches inside, in other words it is like two keys in one. This makes it possible to connect one contact across the CTRL key and the other across the left arrow. There are also electronic ways to do...
by Nasta
Fri Sep 17, 2021 1:18 pm
Forum: Hardware
Topic: ULA1 nextgen idea...
Replies: 31
Views: 7679

Re: ULA1 nextgen idea...

Anyway back on topic - why did Nasta 'nix' the idea of a combined CPU/ZX8301 plug in PCB? I did not - Sinclair did in a way (more below). Somewhere at the start of the thread it was stipulated that the basic version of this 8301 replacement would be a board that plugs into the original 8301 socket....
by Nasta
Thu Sep 16, 2021 11:34 pm
Forum: Hardware
Topic: Expanding the QL's address space beyond 1M (+primer on building QL compatible machines)
Replies: 30
Views: 8121

Re: Expanding the QL's address space beyond 1M (+primer on building QL compatible machines)

At this point, we have almost defined a full 'to do' list on reconstructing the original QL motherboard. Only a few things remain: 1) Expansion port and ROM port enhancements Some signals on the expansion port were never used and some can be re-defined. This is especially pertinent regarding signal ...
by Nasta
Wed Sep 15, 2021 1:42 pm
Forum: Hardware
Topic: ULA1 nextgen idea...
Replies: 31
Views: 7679

Re: ULA1 nextgen idea...

The original pinout of the 8301 limits things quite a lot, it would be interesting to define some ground rules of the project with this in mind... and then the general context, scope and limitations.
by Nasta
Mon Sep 13, 2021 12:32 pm
Forum: Hardware
Topic: ULA1 nextgen idea...
Replies: 31
Views: 7679

Re: ULA1 nextgen idea...

ULA1 = ZX8301 ULA chip (Video and RAM control)
ULA2 = ZX8302 ULA chip (I/O, RTC, IPC comms)
by Nasta
Mon Sep 13, 2021 10:20 am
Forum: Hardware
Topic: ULA1 nextgen idea...
Replies: 31
Views: 7679

Re: ULA1 nextgen idea...

OK, this needs to step back a few steps - are we talking about an ULA1 pin-to-pin replacement or a new chip or board that goes into new hardware (new motherboard etc...)? Asking because a good definition is needed or the thread title might be misleading. If it is a compatible replacement, a refreshe...
by Nasta
Mon Sep 13, 2021 12:32 am
Forum: Hardware
Topic: Expanding the QL's address space beyond 1M (+primer on building QL compatible machines)
Replies: 30
Views: 8121

Re: Expanding the QL's address space beyond 1M (+primer on building QL compatible machines)

Now that I have thoroughly thrashed the 8302-IPC combo :) it is time to shortly return to the 8301. There are two aspects of the 8301 which need to be considered and they are to an extent dependent on each other. The 8301 plays two roles in the QL, and that is the main decoder that maps the ROM, RAM...
by Nasta
Sat Sep 11, 2021 10:55 pm
Forum: Hardware
Topic: Expanding the QL's address space beyond 1M (+primer on building QL compatible machines)
Replies: 30
Views: 8121

Re: Expanding the QL's address space beyond 1M (+primer on building QL compatible machines)

The 8302 ULA As was mentioned before, the 8302 ULA is the main CPU's gateway to all of the I/O devices on the QL motherboard. This consists of the IPC link, serial transmit, net I/O and microdrives. In addition, the ULA implements a reset circuit, interrupt logic, and a real time clock, with a (not ...
by Nasta
Fri Sep 10, 2021 5:13 pm
Forum: Hardware
Topic: Expanding the QL's address space beyond 1M (+primer on building QL compatible machines)
Replies: 30
Views: 8121

Re: Expanding the QL's address space beyond 1M (+primer on building QL compatible machines)

Going back to the original post Would it make sense to have all RAM in low memory (with the QL I/O area blocked out and better decoded) and have ROM overlayed at startup for the first 2 vectors. The ROM can then be anywhere in memory map that's convenient, and some part of it could be copied back i...