Search found 142 matches

by cmorley
Thu Aug 06, 2020 8:46 pm
Forum: ELECTRONICS
Topic: The Myth of Three Capacitor Values
Replies: 4
Views: 190

Re: The Myth of Three Capacitor Values

Analysing it is very complicated - you're in to modelling rather than beard stroking. I just use one value 100nF everywhere... one per power pin... keeps the BOM down to one type of cap and I've never had a problem with any PCB I've done that way. I'll use other values where datasheets ask (mainly p...
by cmorley
Thu Jul 30, 2020 1:48 pm
Forum: PC FOR SALE & WANTED
Topic: For Sale: 27C400 EPROM emulators (beta) issue D
Replies: 60
Views: 19165

Re: For Sale: 27C400 EPROM emulators (beta) issue D

Yes same price still. I'll PM you.
by cmorley
Thu Jul 30, 2020 1:21 pm
Forum: PC FOR SALE & WANTED
Topic: For Sale: 27C400 EPROM emulators (beta) issue D
Replies: 60
Views: 19165

Re: For Sale: 27C400 EPROM emulators (beta) issue D

I have kept back a few modules for forum members' projects. So there are still a few available if you want one or two.
by cmorley
Thu Jul 30, 2020 11:30 am
Forum: MEMBER BLOGS
Topic: Stuff and Things.
Replies: 280
Views: 29821

Re: Stuff and Things.

rubber_jonnie wrote:
Thu Jul 30, 2020 10:19 am
That damn mobo socket is so easy to get wrong :(
I don't know what happens if you plug one of my EPROM emus 1 pin off in a 42 pin socket... it might survive or kill one of the buffers, I'm not sure. Best not to try :?
by cmorley
Thu Jul 30, 2020 10:02 am
Forum: MEMBER BLOGS
Topic: Stuff and Things.
Replies: 280
Views: 29821

Re: Stuff and Things.

@cmorley Would your ROM emulator work in this scenario? The original ROM is 512KB. I note that the 27C800 is 42 Pin, so wondering what my options are if I need to burn my own. If it needs a 27C800 then yes the emulator should work. Pin 1 is A18 and pin 42 is NC on an M27C800 (1MB). Best thing to do...
by cmorley
Sat Jul 18, 2020 8:57 am
Forum: HARDWARE DISCUSSIONS
Topic: Memory current demand
Replies: 7
Views: 238

Re: Memory current demand

PaulJ wrote:
Sat Jul 18, 2020 12:15 am
Hmm, 1 meg machine, 32 memory devices, 32 x .3 = 9.6 amps..
You've got an arithmetic error here...

OP was mW not mA

300mW @ 5v = 60mA.
by cmorley
Mon Jul 06, 2020 8:36 pm
Forum: PC FOR SALE & WANTED
Topic: For Sale: 27C400 EPROM emulators (beta) issue D
Replies: 60
Views: 19165

Re: For Sale: 27C400 EPROM emulators (beta) issue D

I can't do 5. I have a very limited number and won't be making any more of this design. I'd like to make sure hobbyists on this forum can get one or two if they want them.
by cmorley
Wed Jun 24, 2020 11:46 am
Forum: CHAT FORUM
Topic: CPLD, Verilog and universe.
Replies: 19
Views: 1993

Re: CPLD, Verilog and universe.

I would recommend you find a project that you would like to solve. I learnt verilog by implementing a ULA and glue logic on an 8-bit machine copro card. Far more motivating and instructive than following some "blinky" type tutorial IMO.
by cmorley
Thu Jun 18, 2020 10:47 pm
Forum: PC FOR SALE & WANTED
Topic: For Sale: 27C400 EPROM emulators (beta) issue D
Replies: 60
Views: 19165

Re: For Sale: 27C400 EPROM emulators (beta) issue D

More coming in a week or so. I'll assemble some this weekend.
by cmorley
Wed Jun 17, 2020 9:40 am
Forum: 8 BIT CORNER
Topic: 27C400/27C800 EPROM emulator
Replies: 120
Views: 45027

Re: 27C400/27C800 EPROM emulator

I am so cramped for space on this thing there is no chance to fit on any isolation... I don't think it would entirely mitigate the risk to the PC of hot plugging the 0.1" headers. The solution is to use a connector designed for hot plugging - but I don't see how to physically fit one! I could shuffl...

Go to advanced search