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 8/E. Kyle
