I-4004

[ben]

On 2021-11-16 5:08 p.m., jim stephens via cctalk wrote:
> 
> 
> On 11/16/2021 2:20 PM, Al Kossow via cctalk wrote:
>> On 11/16/21 2:08 PM, Murray McCullough via cctalk wrote:
>>> Did the 4004 chip start our interest in microcomputing? 
>>
>> no
>>
>>
> I got interested in microprogramming  before it was hijacked as a a term 
> for such devices.  It's generous at best to apply that term to a 4004 
> anyway.
> 
> In 1971 firmware and the like still was still very much something that 
> was used in conjunction with system design.  A group was very active, 
> SIGMicro to share techniques.  Only after most microprogramming vanished 
> into a black hole in the silicon did it taper off.
> 
> I'm glad some amount of that discipline has emerged in that context, and 
> not applied to small ceramic chips with gold legs.
> 
> thanks
> Jim
> 
Only looking back now at the price and speed of main memory, I can see 
micro-programming advantage. Having the word settle on 8 bit bytes;
(my vote was for 10 bits : 2 BCD digits + sign flag + end flag)
You have a severe lack opcode space as every thing is n+ bytes, compared 
to when you could design the CPU to what ever word sized you needed and 
room for micro-coded ops
and full alu rather than ADD DCA AND OPERATE.
Ben.


Back then you touch the hardware.