Threaded Mode | Linear Mode

polbit · 12-19-2023, 06:56 PM

I am a big fan of the PC-1500(A) in the Sharp pocket computer line. Great machine, but a little bulky. With that in mind, and of course looking for a bigger screen, I was lucky to find a basically new PC-1360. Seemed like a great tradeoff to trying to cary G850. Have been playing with it for the past few days, and I have to say, nice machine, but it is slow...

Comparing CPUs, 1500 has a 1.3MHz LH5801 while 1360 uses SC61860 at (I believe) 768KHz. Running any non-trivial BASIC program, the 1360 takes about twice as long, or longer to complete. Graphics are not really feasable from BASIC. All in all, a bit of a disappointment, I was expecting it to be faster, not so much slower.

Dave Britten · 12-21-2023, 04:39 PM

The CPU in the PC-1500 is quite a bit beefier, as evidenced by needing 4 AA batteries to power it. The PC-1360 and its smaller kin in the 1250, 1260, and 1400 families don't do too bad for running on a couple CR2032s.

xerxes · 12-22-2023, 01:51 AM

(12-19-2023 06:56 PM)polbit Wrote: Comparing CPUs, 1500 has a 1.3MHz LH5801 while 1360 uses SC61860 at (I believe) 768KHz.

Dave is right. The CPU clock of the LH5801 is 2.6 MHz (1.3 MHz machine cycle) vs 0.768 MHz (0.256 MHz machine cycle) of the SC61860.
At the same clock frequency the PC-1360 would be slightly faster.

robve · 12-22-2023, 02:07 AM

(12-19-2023 06:56 PM)polbit Wrote: I am a big fan of the PC-1500(A) in the Sharp pocket computer line. Great machine, but a little bulky. With that in mind, and of course looking for a bigger screen, I was lucky to find a basically new PC-1360. Seemed like a great tradeoff to trying to cary G850. Have been playing with it for the past few days, and I have to say, nice machine, but it is slow...

As Dave Britten said, it's not that bad for an 80s machine running on just two CR2032s. But you are not alone. I felt the same way back in the mid 80s when I purchased a PC-1350. Nevertheless, I got the most out of it by discovering it also has the DEF-AREAD combo to write a library of math routines and using a CE-126p printer to save/load programs. Writing assembly was cool too, but very different than 8080/Z80/6502/6809 which are all easier to write. The PC-1350/1360 is a lot more portable. And no danger of leaking AA cells. The CR2032 cells last a long time.

The E500 hits the middle in terms of size, with a punchy CPU and large LCD. It is smaller and lighter than the PC-1500, but not as small and light as the PC-12xx, PC-13xx, and PC-14xx series. The E500S version on the other hand is a bit larger, but has a better LCD compared to the E500. Neither have DEF-AREAD which is a shame. No RTC either, which the PC-1500/1600 have. But it has programmable menus. The PC-G850 is OK, but not as good as the E500, especially the E500 ROM system is well designed and documented when that matters e.g. in assembly code.

- Rob

polbit · 12-22-2023, 02:07 AM

(12-22-2023 01:51 AM)xerxes Wrote:
(12-19-2023 06:56 PM)polbit Wrote: Comparing CPUs, 1500 has a 1.3MHz LH5801 while 1360 uses SC61860 at (I believe) 768KHz.

Dave is right. The CPU clock of the LH5801 is 2.6 MHz (1.3 MHz machine cycle) vs 0.768 MHz (0.256 MHz machine cycle) of the SC61860.
At the same clock frequency the PC-1360 would be slightly faster.

Looking at the PC-1500 Technical Service Manual, it clearly states that the CPU gets a 1.3MHz clock. The crystal is 2.6MHz, but it's divided to drive the clock. Am I missing something here? I can't find similar information for the SC61860.

polbit · 12-22-2023, 02:14 AM

(12-22-2023 02:07 AM)robve Wrote:
(12-19-2023 06:56 PM)polbit Wrote: I am a big fan of the PC-1500(A) in the Sharp pocket computer line. Great machine, but a little bulky. With that in mind, and of course looking for a bigger screen, I was lucky to find a basically new PC-1360. Seemed like a great tradeoff to trying to cary G850. Have been playing with it for the past few days, and I have to say, nice machine, but it is slow...

As Dave Britten said, it's not that bad for an 80s machine running on just two CR2032s. But you are not alone. I felt the same way back in the mid 80s when I purchased a PC-1350. Nevertheless, I got the most out of it by discovering it also has the DEF-AREAD combo to write a library of math routines and using a CE-126p printer to save/load programs. Writing assembly was cool too, but very different than 8080/Z80/6502/6809 which are all easier to write. The PC-1350/1360 is a lot more portable. And no danger of leaking AA cells. The CR2032 cells last a long time.

The E500 hits the middle in terms of size, with a punchy CPU and large LCD. It is smaller and lighter than the PC-1500, but not as small and light as the PC-12xx, PC-13xx, and PC-14xx series. The E500S version on the other hand is a bit larger, but has a better LCD compared to the E500. Neither have DEF-AREAD which is a shame. No RTC either, which the PC-1500/1600 have. But it has programmable menus. The PC-G850 is OK, but not as good as the E500, especially the E500 ROM system is well designed and documented when that matters e.g. in assembly code.

- Rob

I think I'm starting to appreciate 1500 more and more, and will just have to get my hands on the 1600! While I started this thread (and my purchase) with an idea of a smaller machine, I just don't find the trade-offs worthy for my use.

xerxes · (This post was last modified: 12-22-2023 09:11 AM by xerxes.)

(12-22-2023 02:07 AM)polbit Wrote: Looking at the PC-1500 Technical Service Manual, it clearly states that the CPU gets a 1.3MHz clock. The crystal is 2.6MHz, but it's divided to drive the clock. Am I missing something here? I can't find similar information for the SC61860.

The 1.3 MHz refers to the machine cycle, mentioned on page 23 in Assembly Language Manual and on page 9 in Technical Reference Manual. The information about the SC61860 is from a German book about the assembly language of this CPU.

polbit · 12-22-2023, 01:15 PM

(12-22-2023 03:48 AM)xerxes Wrote:
(12-22-2023 02:07 AM)polbit Wrote: Looking at the PC-1500 Technical Service Manual, it clearly states that the CPU gets a 1.3MHz clock. The crystal is 2.6MHz, but it's divided to drive the clock. Am I missing something here? I can't find similar information for the SC61860.

The 1.3 MHz refers to the machine cycle, mentioned on page 23 in Assembly Language Manual and on page 9 in Technical Reference Manual. The information about the SC61860 is from a German book about the assembly language of this CPU.

I think some of the facts are getting lost in translation here. To summarize:

PC-1500 uses LH5801. It has a 2.6MHz external crystal that is divided by 2 for the internal clock that runs the whole system, including the CPU. That means that the CPU speed is 1.3MHz.

Page 9 of PC-1500 Technical Reference Manual:
"These are external crystal connection pins. XL0 is the input pin and XL1 is the output pin. Clock frequency is divided by two inside the CPU. When the 2.6MHz crystal is connected the CPU operates under 1.3MHz of internal machine cycle."

Page 10 of PC-1500 Technical Reference Manual:
"Connection of the 2.6MHz crystal oscillator to XLO and XLI wil supply the clock of 1.3MHz."

PC-1360 uses SC61860. It has a 768KHz external crystal that drives the CPU without a divisor, therefore the CPU speed is 768KHz, or abour 41% slower than PC-1500 on per cycle basis. Good start to explain the performance difference without accounting for architecture.

Page 30 of PC-1350 Machine Language Reference Manual:
"The PC-1350 operates on dc 5-volt power supply and runs on the 768 KHz basic system clock. The basic system clock is generated in the CPU. The clock frequency is derived from the 768 KHz quartz crystal which is external to the CPU."

toml_12953 · 12-22-2023, 07:49 PM

(12-22-2023 02:14 AM)polbit Wrote: I think I'm starting to appreciate 1500 more and more, and will just have to get my hands on the 1600! While I started this thread (and my purchase) with an idea of a smaller machine, I just don't find the trade-offs worthy for my use.

I looked at all the pocket computers available. Since I program in BASIC, I finally chose a Sharp PC-E500S since it had the most powerful BASIC of any handheld other than the HPs which were out of my price range. 1500 and 1600 BASIC both limit arrays to 255 elements in each dimension:
DIM A(256) will give an error. This is too limiting for me. The PC-E500S has IF..THEN...ELSE...ENDIF (in addition to the older, single-line IF THEN) as well as SWITCH...ENDSWITCH, REPEAT...UNTIL and WHILE...WEND all of which make programming it a joy. Also I have a 256K RAM module for a total of 288K RAM, all directly usable by BASIC. My system includes the CE-126 thermal printer/cassette interface with the Sharp cassette recorder/player, and an RS-232 serial port that drives a Sharp CE-515P color plotter/printer.
I'm pretty happy with the setup.

xerxes · 12-23-2023, 12:29 AM

(12-22-2023 01:15 PM)polbit Wrote: I think some of the facts are getting lost in translation here.

I think you are right.

I`ve compared the number of the instruction cycles of the LH5801 with other CPUs for plausibility and apparently the term machine cycle is misleading in the LH5801 documents.
In the documentations of other CPUs like Z80, SC61860 or HD61700 there is a clear distinction between clock cycle (T-State) and machine cycle. I'll correct the benchmark list.

Thanks for your attention.