22 Sep
2015
22 Sep
'15
3:29 p.m.
On 09/22/2015 01:35 PM, Rick Bensene wrote:
There were no index registers on this machine, only a
single
accumulator register (implemented as a shift-register).
Not that uncommon, really. It was only Model II of the 1620 that had
index registers; the CADET didn't. No accumulator either--just a simple
2-address architecture. It did have (optional) indirect addressing,
however, which was a godsend if you had it. Otherwise, you really did
have to plug instructions.
But even the 650 had a TLU instruction...
--Chuck