I removed both samples from the board (a defunct PCI VGA card), and if they're of any use you're welcome to them, Bill. It'd be easy enough to slip them in the mail. Thanks for the offer Jeff, I really appreciate it but I'd have no way to solder those sockets on. Seems bit weird to put an SMD ...

no idea if anyone asked for this, but i also made an adapter. mostly because i wanted to experiment with the ATF1504 before putting it into my SBC.
20200519_201132.jpg
it doesn't have a key'd JTAG connector and obviously is a lot wider than cbscpe's design (which means you likely need 1 ...

But I see people running 6502s at 750 KHz all the time, so perhaps the data sheet is a bit conservative?
Those people include owners of the Microtan 65 , a 1979 machine that was designed to run at 750kHz (because they wanted a CPU speed that was a subdivision of the 6MHz clock they needed for ...

The TIM schematic is very simple, that’s part of the appeal, and I was impressed that it only used a 7400 and 7404 for the address decoding (not that there is much to decode as some of it is done internally in the 6530). I’ve been sidetracked over the last few days understanding it and modifying it ...

I've used a can oscilator with a Rockwell 6502P (running at 1MHz) with no complications. See my build thread on the Stardot forums at https://stardot.org.uk/forums/viewtopic.php?t=15387

I used a pair of NOT gates just in case they were really needed in the original design I was replicating, but ...

A "semulator"?

(Not to be confused with an imulator, that's when your power supply catches fire. Or is that an immolator? )

Thanks for all the replies. Responding in no particular order:

BigEd , I hadn't looked in detail at what Acorn did with their 65C02 in the Master range. I wonder if they switched to using the RDY signal because they no longer had the NMOS limitation of RDY only kicking in during read operations ...

I'm bouncing ideas around in my head for a future computer build, which would involve a rehash of Acorn's 6502A microcomputer card as used in their System range (schematics here ), but with additional RAM on board, etc. This card had the feature of allowing the user to select the clock speed from ...

My first taste of computer programming would have been in using Logo on BBC Micros and Archimedes machines. Not exactly sophisiticated stuff, but there waas an element of variables, subroutines, etc.

At secondary school we did a brief session with Logo for Windows. (This confused me a bit as I'd ...

Hi,

Did you ever complete the project? I have yet to start!!

http://forum.6502.org/viewtopic.php?f=12&t=3286&hilit=planning+build+acorn#

Just stumbled across this post while looking to reference what I'd learned about oscillator circuits; sorry for the late reply!

I made a build thread over on ...

Congratulations!

May I asked how many inverters/buffers you have left in your oscillator circuit?

I used the two LS04 inverters that were used in the original circuit. Thus, except for the use of a can oscillator instead of a crystal and resistor, the whole board* is wire-for-wire equivalent to ...

For anyone who's interested, I've succeeded in getting my System 1 clone running. (Cassette interface is pending.) I've got a write-up of the build on the Acorn-oriented Stardot forums.

I now have a nice platform for playing around with some 6502 assembly in the future!

Placing the hold is what activates the pump in the first place. The hold is supposed to be replaced by the actual purchase on the second swipe, but procedures are a bit sloppy in practice.

Second swipe, eh? In the UK, paying for fuel by pre-authorised debit/credit card instead of going to the ...

Amusingly, one of the few machines to directly support the Kansas City tape format was the BBC Micro. But even then, most tapes actually used a faster 1200 baud variant, rather than the 300 baud standard - and 1200 baud was the default.

Probably more people are familiar with the ZX Spectrum's tape ...

First, just to say, I've been lurking here for far too long :oops: I'll try to make an effort to post more often... So hello to those who don't know me from other forums.
My first thought was "you're not lurking, I've read loads of your posts", then I realised I wasn't thinking of this forum ...