Search found 337 matches

by McKlaud
Mon Jul 04, 2022 1:38 pm
Forum: Hardware
Topic: Timex 2048 only 16k
Replies: 49
Views: 10082

Re: Timex 2048 only 16k

The latest and most accurate schematic of Timex Computer 2048, PCB rev 5 attached. Is this different to the version here ? Yes, It is. The version (1.3) in the linked tread had a few errors, that been corrected in the latest rev 1.8. I will zip the latest schematic and attach here when I am back ho...
by McKlaud
Sun Jul 03, 2022 6:40 pm
Forum: Hardware
Topic: RAMPACK and Hi-RES mod ?
Replies: 23
Views: 12273

Re: RAMPACK and Hi-RES mod ?

I have never mentioned about NAND gate for /RD and /RFSH. AND gate is needed, so 2 diodes and resistor can do the trick. This AND gate is essential for external RAM packs built with dynamic RAM chips.
by McKlaud
Sun Jul 03, 2022 6:34 pm
Forum: Hardware
Topic: Timex 2048 only 16k
Replies: 49
Views: 10082

Re: Timex 2048 only 16k

The latest and most accurate schematic of Timex Computer 2048, PCB rev 5 attached.
by McKlaud
Thu Nov 11, 2021 6:22 am
Forum: Hardware
Topic: Spectrum error
Replies: 20
Views: 6261

Re: Spectrum error

It might be speculation if M1 issues were related to any Z80 brand fitted in the factory. But M1 fault is only related to some Z80 made by Zilog in 80-ies. Nobody reported such issue with factory fitted NEC or SGS made CPU's. Not fully functional Z80'ies in ZX Spectrums might be a result of a cost s...
by McKlaud
Wed Nov 10, 2021 8:58 pm
Forum: Hardware
Topic: Spectrum error
Replies: 20
Views: 6261

Re: Spectrum error

M1 line is not used in ZX Spectrum. Many of ZX Spectrum left factory with faulty/non-active M1 line in the fitted Z80.
by McKlaud
Wed Nov 10, 2021 9:49 am
Forum: Hardware
Topic: 128K Toastrack Lower RAM Fail
Replies: 12
Views: 3578

Re: 128K Toastrack Lower RAM Fail

Yes, just corrected.

The data sheet attached.
by McKlaud
Wed Nov 10, 2021 6:27 am
Forum: Hardware
Topic: 128K Toastrack Lower RAM Fail
Replies: 12
Views: 3578

Re: 128K Toastrack Lower RAM Fail

KM41464's are not good for Toastrack, because they are 4bit DRAMs and were used in +2A/B and +3.

For Toastracks and the upper RAM of any Spectrum 48K, suitable Samsung brand chips are KM4164B
by McKlaud
Sun Nov 07, 2021 8:14 am
Forum: Z88
Topic: Diagram for making your own cartridges?
Replies: 15
Views: 14816

Re: Diagram for making your own cartridges?

Wow! This is impressive.

One comment, the cartridge seems to be too wide and it would not fit into the slot.

There are no contacts on the other side because sockets are single sided. See photos.
by McKlaud
Tue Nov 02, 2021 6:21 am
Forum: Z88
Topic: Diagram for making your own cartridges?
Replies: 15
Views: 14816

Re: Diagram for making your own cartridges?

Hi, please see the attached.
by McKlaud
Fri Oct 08, 2021 9:09 am
Forum: Hardware
Topic: BT audio & wireless tape loading to ZX81
Replies: 1
Views: 1334

Re: BT audio & wireless tape loading to ZX81

The external BT module for ZX family, just tested with a ZX Spectrum clone. Have a look there: https://youtu.be/rLYKKHdo0hs

Tests with ZX81 and Jupiter ACE will follow soon.