System360 Hardwired vs. Microcoded 397

At HP we went though what I believe was a similar exercise with the HP 3000 Series 64. When VISION was delayed in lieu of SPECTRUM, the 3000 product line was in a bad place with no imminent performance upgrade in the pipeline. As a stop-gap measure we shipped disc-caching as the Series 68 and Series 70. When the customer upgraded they got a new face-plate (64-68) and a microcode tape. I believe the 70 included additional memory (important for disc caching). But, many customers were under-whelmed with the amount of change they saw for the dollars they paid. However, a great product with lots of customer benefit that really saved HP's bacon at the time.

Sounds like the 168 was a field upgrade from the 165. Was the original 165 designed to accommodate virtual memory, or was VM an after-thought?

On a related note I am buttuming that the 158 did not share any lineage with the 155? That the 155 was more a backwards leaning 360'ish machine than forward leaning 370 architecture machine. The timing of the 155-165 relative to the 158-168 announcements might lead one to believe there was some linkage between the systems.

Thanks!

Lee Courtney