PDP-8/I vs 8/E EAE
bobsmithofd at gmail.com
Tue Mar 2 16:23:08 CST 2021
Don't know if you have seen this - might be helpful
On Tue, Mar 2, 2021 at 3:09 PM Kyle Owen via cctalk
<cctalk at classiccmp.org> wrote:
> Has anyone noticed a difference in DVI overflow behavior on the PDP-8/I EAE
> versus the PDP-8/E EAE? The 8/E EAE claims to be 8/I compatible in Mode A,
> and I think I agree, for the most part. At least, it's compatible for the
> parts that matter.
> When a DVI instruction results in overflow, the EAE immediately returns
> with the link set. The results in AC and MQ seem to have no relevance, but
> they appear to differ between the 8/E and 8/I.
> For instance, running the 8/I MUY/DVI diagnostics under SimH fails due to
> the following:
> sim> lo maindec/maindec-8i-d0ba-pb.bin
> sim> d sr 40
> sim> g 201
> DIVERR L C(AC) C(MQ) C(MB)
> PROB 0 000000000000 000000000000 000000000000
> GOOD 1 111111111111 000000000000 000000000000
> BAD 1 000000000000 000000000001 000000000000
> SCA 000000000000
> HALT instruction, PC: 01512 (JMP I 1506)
> The link is set, but obviously MQ and AC do not match.
> Running the same diagnostic on an 8/I works fine.
> I can't imagine a scenario outside of diagnostics where this behavior would
> impact the software, but it does seem curious nevertheless that the DVI
> approach to handling overflow differs slightly between EAEs on the 8/I and
More information about the cctech