Image Map Image Map
  • SiriusHardware's Avatar
    Today, 09:07 AM
    Glad those ICs turned out OK, as I had no actual system to test them in. It'll be nice to see the machine doing something when you eventually get...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    Today, 06:07 AM
    I meant that it is traditionally considered bad form to connect logic inputs directly to V+ rather than through a pullup resistor.
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 20th, 2017, 09:07 AM
    Looking back again at the version of the diagram Lurch posted a link to in #2 of this thread, I notice that the video RAM is actually stated (in that...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 18th, 2017, 04:33 PM
    Lurch, good work. I'll be keeping an eye out for your blank devices arriving, will let you know via PM when they have arrived and I'll try to turn...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 10th, 2017, 02:19 PM
    Just to be clear, you mean a RAM which has a slower (higher) marked nanosecond speed on the end of the part number? If so, what is the marked...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 8th, 2017, 10:43 AM
    Worth a try, though? It would be an easily reversible mod. A capacitance selection box, as per an earlier suggestion, would be useful. If this was...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 8th, 2017, 09:02 AM
    Daver2. sounds like you need to offer to 'borrow' your old Nascom 2 back for a while (so you can fix it, obviously). With regard to the potential...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 7th, 2017, 11:37 AM
    Ref: IC49 making a difference, do you have any freezer spray handy? What happens if you let the fault clear up and then you cool the 16Mhz oscillator...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 7th, 2017, 06:18 AM
    To be honest I'm having trouble with the idea of RAM which is too fast. Normally the system asserts _CE and _RD, and the RAM outputs its data in good...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 5th, 2017, 12:20 PM
    OK, let's see what happens when you get your new video chip set - I agree that changing a set of socketed chips is easier to do first than checking...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 4th, 2017, 03:43 PM
    Lars, the first thing I notice from what you say is that there are no old passives in the working machine. It would not be a trivial step, but as a...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 4th, 2017, 04:33 AM
    Lars, thanks for persevering despite the difficulties you had posting. Since you are in the incredibly fortunate position of having one working...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 2nd, 2017, 03:08 PM
    Section 3.1 of the manual (Video troubleshooting) makes it very clear that the 74LS13s were introduced to clean up problems which were occurring...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 2nd, 2017, 09:39 AM
    If, as daver2 says, some versions of the diagram (and the parts list) say that IC71 is a 74LS13 then that's undoubtedly why your machine has them...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 1st, 2017, 05:41 PM
    Just looked it up - not an equivalent exactly - both ICs are dual 4-input NAND gates with the same pinout on each of their two gates, but the 7420's...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    June 1st, 2017, 10:18 AM
    I'm not sure if I missed a discussion of a mod somewhere in this interesting thread, but looking at the diagrams Lurch referenced in post #2 I see...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    May 29th, 2017, 11:27 PM
    SN, DM, etc on the front of a logic IC number is just the manufacturer's badge - the 74xx and 4xxx logic family series were produced by quite a few...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    May 26th, 2017, 09:06 AM
    Thanks Malc, I've had the same information from several other people, that the 'C' denotes the package. We have a Needhams EMP-20 programmer at work,...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    May 25th, 2017, 03:11 PM
    Ok, I found a fantastic online archive of old IC databooks. This PDF here - "Motorola Memory Device Databook 1984" - has a section on the MCM68766...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    May 25th, 2017, 11:03 AM
    No problem with the N82S23N PROM which I can definitely do. Just checking to see whether my programmer supports the MCM device... Close, but...
    134 replies | 5949 view(s)
  • SiriusHardware's Avatar
    May 24th, 2017, 11:33 AM
    Reading back through daver2's musings it seems there are supposed to be ten unused memory locations per character line in the left margin of the...
    134 replies | 5949 view(s)
No More Results
About SiriusHardware

Basic Information

About SiriusHardware
Location:
UK

Statistics


Total Posts
Total Posts
158
Posts Per Day
0.13
General Information
Last Activity
Today 01:17 PM
Join Date
February 15th, 2014
Referrals
0