Search found 11 matches

by tynemouthsoftware
Thu Nov 12, 2020 11:25 pm
Forum: Development
Topic: ZX81 Clone Tynemouth Minstrel 3
Replies: 48
Views: 23682

Re: ZX81 Clone Tynemouth Minstrel 3

I think the new chips should help. I am not saying the HCT versions will be better than HC (they didn't make a difference for me), but if flaky chips were the issue, then the new ones should get you working.
by tynemouthsoftware
Wed Nov 11, 2020 7:18 pm
Forum: Development
Topic: ZX81 Clone Tynemouth Minstrel 3
Replies: 48
Views: 23682

Re: ZX81 Clone Tynemouth Minstrel 3

Swapping IC25 HC257 for an HCT257 should not cause a problem if that works out better. I would suggest changing IC24 as well, so the keyboard response is identical. The other inputs are near by HC outputs so HCT should be OK. https://1.bp.blogspot.com/-geP_0jMQUaQ/XeKWTuIkwhI/AAAAAAAATKI/sMxdeEzyAXM...
by tynemouthsoftware
Wed Nov 11, 2020 10:48 am
Forum: Development
Topic: ZX81 Clone Tynemouth Minstrel 3
Replies: 48
Views: 23682

Re: ZX81 Clone Tynemouth Minstrel 3

Are you sure the Minstrel is OK? could be a short or a dry joint one one of the pins, wrong values (particularly easy with the 47nF/47pF caps), or a flaky 74HC257.

Saving and reloading works on all the Minstrels I have built, as does direct from TZXduino, so I may be worth double checking your build.
by tynemouthsoftware
Tue Nov 10, 2020 11:09 pm
Forum: Development
Topic: ZX81 Clone Tynemouth Minstrel 3
Replies: 48
Views: 23682

Re: ZX81 Clone Tynemouth Minstrel 3

That's neat, but looks like it would work similarly to the TZXduino in the way it interfaces to the ear port. I think you said you were having problem with loading from that into the Minstrel? I got the best results with my bodged together TZXduino with all of the analogue circuitry on the output mi...
by tynemouthsoftware
Mon Jan 20, 2020 12:22 pm
Forum: Development
Topic: ZX81 Clone Tynemouth Minstrel 3
Replies: 48
Views: 23682

Re: ZX81 Clone Tynemouth Minstrel 3

Looks interesting. A couple of questions. What extra software can you now run with the 56K RAM that couldn't run before, and are there any programs which did run with 16/32K but will not work with the extra RAM? I have not found much software which needs more that the standard 16K, so trying to judg...
by tynemouthsoftware
Thu Jan 09, 2020 1:05 pm
Forum: Development
Topic: ZX81 Clone Tynemouth Minstrel 3
Replies: 48
Views: 23682

Re: ZX81 Clone Tynemouth Minstrel 3

The Minstrel 2 and Minstrel 3 are both ZX81 shaped, so will not fit in a ZX80 case. They are designed to be used in a ZX81 case or standalone.

There are some ZX80 clones that are the right shape and size for a ZX80 case, but the Minstrel boards are not.
by tynemouthsoftware
Sat Jan 04, 2020 8:25 pm
Forum: Development
Topic: How to enable ZX-Key external keyboard with Minstrel 3 board
Replies: 8
Views: 3000

Re: How to enable ZX-Key external keyboard with Minstrel 3 board

One option I suggested when this was first raised was to swap out the 257s that are used for the keyboard read with 74LS257s. The LS is good at pulling down, but has a weak pull up. If the ZX-Key interface is driving low strongly with it's HCT245, that may be enough to register? The main thing those...
by tynemouthsoftware
Thu Jan 02, 2020 11:20 am
Forum: Development
Topic: ZX81 Clone Tynemouth Minstrel 3
Replies: 48
Views: 23682

Re: ZX81 Clone Tynemouth Minstrel 3

Thanks for posting the findings, interesting to see how that worked out. I had tried to remove as many of the analogue bits of the design like those RC filters, but had to leave those in as I couldn't get the timing right using the synchronous 74166 rather than the giving a short pulse to the non-sy...
by tynemouthsoftware
Thu Jan 02, 2020 11:00 am
Forum: Hardware
Topic: Which ROM for Minstrel 3?
Replies: 21
Views: 2755

Re: Which ROM for Minstrel 3?

Thank you, I'm pleased you appreciate the work that went into the layout of the Minstrel boards. The ROM can be the standard ZX81 ROM. I suggest using all the jumpers high to allow compatibility with the most types of EPROM. The pins that are used for the higher address lines on a 27C512 are used fo...
by tynemouthsoftware
Fri May 04, 2018 11:11 pm
Forum: Hardware
Topic: zx spectrum in zx81 case
Replies: 63
Views: 25115

Re: zx spectrum in zx81 case

I also had an issue with one of the clocks, but in my case it was the 4.43MHz clock used for the colour timing. I used an 74HCU04 (the same as used on the +2 if I remember correctly). http://blog.tynemouthsoftware.co.uk/2018/02/keyboard-options-for-zx-max-48.html If the 14Mhz isn't running, that mig...