View Single Post
Old 9th Apr 2019, 6:59 pm   #155
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,485
Default Re: MK14 schematic revisions

(Keeping the more general MK14 related questions in this thread).

Timbucus: regarding your suspected faulty INS8154, RAM/IO IC, how did you come to that conclusion?

The RAM/IO has three 'images' in memory at 0800 onwards, 0C00 onwards and 0E00 onwards. For the purposes of this, let's stick with the one at 0800 onwards.

The 128-byte RAM portion of the device is mapped into the upper half of the 256-byte block occupied by the RAM/IO, therefore at 0880-08FF. You should find that data entered anywhere within that address range will 'stick'.

If you tried it out by editing addresses low down in the RAM/IO block and expecting them to read back the same, 0800 - 0824 are the control / data registers etc of the I/O portion of the device, so writing to those locations and then looking at them would give unexpected results.

Addresses 0x0825-0x087F do not (officially) have any hardware associated with them, so anything written to that range would be lost.
SiriusHardware is offline