HP LogicDart CPU?

[Jonathan Busby]

I've slowly been fixing inaccuracies and other problems in the Wikipedia HP Saturn article before I completely overhaul it ( although I haven't had much free time as of late to dedicate to HP calculator related activities ). In this regard, I wanted to add a reference to a reliable source that the HP ( and later Agilent ) "LogicDart" hand-held logic analyzer used a Saturn CPU/SoC. But, after some in-depth googling, I came across this forum post, which I'll post, Google machine translated from French, below :

Quote:Coming from the calculators part, we find a screen derived from that of the HP 48 but with more contrast (same definition: 131 x 64-pixel, but without the line of indicators and therefore with 10% higher pixels). There is also the possibility of infrared printing on a portable HP 82240B printer.

On the other hand it does not use the Saturn processor of the HP-48, nor the RPL for the software. The LogicDart processor is an Intel 80L188EB controller, integrating a low power x86 core, two UARTs, 2 I / O ports, 3 timers and other peripherals… The software was developed with the C Executive real time system from JMI Software.

The above seems to indicate that the LogicDart did *not* use a Saturn CPU/SoC, but instead an Intel x86-based microcontroller.

I always thought that the LogicDart used a Saturn CPU/SoC and ran an RPL OS due to its menu system being similar to the HP48 and the LCD display also being very similar with the same resolution IIRC.

I don't suppose that anyone has a LogicDart lying around somewhere which they could open up and confirm that the main CPU/SoC is Intel-based and not Saturn-based by reading the silk-screened chip package ID code(s)?

Regards,

Jonathan

[David Bengtson]

In fact, I do have a Logic Dart lying around. If I can figure out how to open it nondestructivly, then I'll do that. Might take me a little time to get to it, thought.

Dave

[teenix]

Some internal pictures here, but cannot make out chip types

http://www.pahhc.org/1997/PAHHCF97.HTM

cheers

Tony

[J-F Garnier]

(09-19-2020 08:43 PM)Jonathan Busby Wrote:  The above seems to indicate that the LogicDart did *not* use a Saturn CPU/SoC, but instead an Intel x86-based microcontroller.

I always thought that the LogicDart used a Saturn CPU/SoC and ran an RPL OS due to its menu system being similar to the HP48 and the LCD display also being very similar with the same resolution IIRC.

There is no doubt that the LogicDart is based on a Intel 80L188 running a RTOS from JMI.
The original well-documented French thread (hello 'zpalm' !) includes a link to an article in Portable Design, March 1998, where Eric Vogel (the R&D project manager for the LogicDart) is quoted and mentioned the processor, among other things. Worth to read.

Also you can find the presentation by Eric Vogel at the PAHHC meeting on June 1997 here, he mentioned the Intel processor too and also said that the RPL was not an option (2h25-2h30).
This (long) session includes a complete live teardown and reassembly of the LogicDart, by Eric. What a great session!

   

J-F

[Jake Schwartz]

I'd love to hear from Eric Vogel again. Last we heard, he was working for Bose in New England. Eric spoke at our Philly-area PAHHC meetings a couple of times, first in '91 when he presented the brand new 32S2 and HP-95LX. He also gave some memorable talks at the Chicago-area CHIP chapter meetings, including one where he charted on a blackboard all the Pioneer variants, with ROM, RAM, CPU and display differences. Of course, the LogicDart visit in '97 was also great. At the end, Jim Lawson was talking to him regarding any possible future of high-end HP calculators beyond the 48gx, which was already 4 years old, and Eric felt that those days had run their course and we were at the end of the line. Meanwhile, in the Fall of that year 1997 at the British HPCC 15th anniversary conference in London, we met the "Metakernel guys", and ultimately that blossomed into the 49G two years later.

Jake

[rprosperi]

(09-21-2020 01:22 PM)Jake Schwartz Wrote:  I'd love to hear from Eric Vogel again. Last we heard, he was working for Bose in New England.

My sister worked at Bose until quite recently, I'll check if there's any trace of him still around.

[Jonathan Busby]

Thanks for all the informative replies! I'll edit the Wikipedia article accordingly and remove the reference to handheld logic analyzers.

Thanks and regards,

Jonathan

[Jonathan Busby]

And, done!

Regards,

Jonathan

[Didier Lachieze]

(09-19-2020 08:43 PM)Jonathan Busby Wrote:  I don't suppose that anyone has a LogicDart lying around somewhere which they could open up and confirm that the main CPU/SoC is Intel-based and not Saturn-based by reading the silk-screened chip package ID code(s)?

And as a final confirmation here is a picture of the board showing the Intel 80L188EB 13MHz SoC.

   

[Jonathan Busby]

(09-22-2020 06:56 PM)Didier Lachieze Wrote:  

(09-19-2020 08:43 PM)Jonathan Busby Wrote:  I don't suppose that anyone has a LogicDart lying around somewhere which they could open up and confirm that the main CPU/SoC is Intel-based and not Saturn-based by reading the silk-screened chip package ID code(s)?

And as a final confirmation here is a picture of the board showing the Intel 80L188EB 13MHz SoC.

Thanks!

Regards,

Jonathan

[J-F Garnier]

(09-22-2020 06:09 PM)Jonathan Busby Wrote:  Thanks for all the informative replies! I'll edit the Wikipedia article accordingly and remove the reference to handheld logic analyzers.

I was re-reading the article and was intrigued by the reference to the Saturn processor in the ThinkJet (and in the IPC built-in printer).
So I had a look at the ThinkJet service manual since this was new to me.

The Saturn is never mentioned in the service manual but surprising the Saturn bus appears in the schematics to drive RAM/ROM chips from the 1LJ7 control IC:
   

The RAM is a 1LK4 (1LG8 in the IPC) similar to the HP-71 1kbyte RAM chips,
the ROM is 1LG7 16kbyte ROM similar to the HP-71 ROM chips.
Curiously, the RAM/ROM chips are housed in big DIP28 packages.

So this could suggest that a Saturn core is used in the 1LJ7 control IC.

But referring to the HP Journal articles on the ThinkJet (May 1985), under the title "Custom VLSI Microprocessor System" , we can read (emphasis added):

"The ThinkJet Printer electronics are based on a custom HP integrated circuit that is a single-chip microprocessor system with a CPU, RAM, ROM, interface, timers, and I/O in one 48-pin package.[..]
Communication with external RAM and ROM is accomplished through a custom 6-bit interface originally designed for the HP-71 Handheld Computer."

Then:

"This architecture uses predesigned macrocells combined with specialized circuitry for special applications. The macrocells
include a high-speed control-oriented 8-bit CPU, a configurable mask-programmed ROM, a configurable RAM,
a programmable timer, an HP-IL interface, a crystal oscillator, a 4-bit test bus, and general-purpose I/O (GP-IO) pad cells.
The ThinkJet IC uses two timers, 160 bytes of RAM, 10K bytes of ROM."

Elsewhere, we can read:

"The character ROM and the buffer RAM are both HP custom parts chosen because of their availability from the
development of an earlier HP product and their minimum number of interface lines. The character ROM is structured
in 4-bit nibbles , an efficient match for the 12-dot-high printhead column and its column-by-column character font representation.
The buffer RAM is also structured in nibbles, which is useful during the accumulation and printing of bit-mapped graphics data."

So the ThinkJet control IC reused the HP-71 Saturn bus for the external RAM (character buffer) and ROM (character bitmap).
But there is no Saturn processor inside the 1LJ7. At least no evidence for it, and strong presumptions for a classic 8-bit microcontroller.

J-F