Teardown & assessment of a brand new 386 system: Hand386

2023-06-05 01:45:18

A brand new 386-based palmtop not too long ago appeared on Aliexpress and was lined by websites like Tom’s Hardware. My curiosity was stoked and I shortly snapped one up.

It’s out of inventory on the time of writing.

Aside from the svelte Hand386, it comes with an entire host of helpful equipment to make it helpful as an expandable desktop system:

2GB Compactflash (CF) card preinstalled with Home windows 95
VGA, PS/2 mouse and keyboard breakout board
2×6 pin 2.00mm pitch IDC ribbon cable
2A USB charger
USB to barrel plug cost cable
Requires add-on buy:
- 3-slot 8-bit ISA extender (requires separate 12V energy provide)
- 2×30 pin 2.00mm pitch IDC ribbon cable

Let’s bounce proper in with a 12 minutes video I product of the system to demo its capabilities.

00:00 – Booting DOS 6.22
00:14 – Descent at lowest high quality
03:01 – Doom at low high quality
05:12 – Planet X3
06:16 – DOS ChatGPT shopper
07:33 – CheckIt 3 system benchmarks
08:54 – Boot Home windows for Workgroups 3.11
09:31 – Startup chime utilizing Adlib wave driver
09:36 – Begin Media Participant to play Canyon.mid
09:57 – Program Supervisor Properties
10:09 – Open Driver Pane to point out Adlib and Adlib wave driver
10:31 – Open USB flash drive and hotswap
11:19 – Closing purposes and exit home windows
11:30 – Exit Home windows chime utilizing Adlib wave driver

Utilizing the 8-bit ISA bus extender card, a 3Com 3C509 NIC and a Blasterboard (Sound Blaster 2.0 clone) was added on. For the DOS purposes, OPL FM and PCM sounds are immediately recorded from the Line out of the Blasterboard. For WFW 3.11, they’re recorded from the Hand386’s headphone jack.

It’s instantly clear that the 386SX-class CPU struggles in operating later DOS video games which is completely anticipated.

I made a 7 minutes video of it operating the 8088 Domination too.

What precisely is a 386?

The Intel 386 CPU was first launched by Intel in 1985. Generally known as 80386 or i386, it’s the first 32-bit CPU of the x86 structure.

Key extra options embody a greater implementation of protected mode which allowed entry as much as 4GB of reminiscence. Packages can now use a flat reminiscence mannequin as a substitute of dealing with messy segmented reminiscence of the previous.

A digital 8086 mode permits a number of 16-bit actual mode applications to run on this protected mode surroundings. Home windows makes use of such a mode to run purposes like DOS applications.

Supply: https://en.wikipedia.org/wiki/I386

The preliminary launch mannequin was known as the i386DX mannequin with 32-bit knowledge bus. The CPU core used within the Hand386 relies on the lower-cost 386SX variant which makes use of solely a 16-bit knowledge bus and solely helps as much as 16MiB of RAM.

This smaller bus additionally hurts the efficiency of the CPU relative to the unique DX variant.

Specs

DM&P Ali M6117 with chipset (386SX-40)
Chips and Tech F65535
YMF262-M OPL3 with YAC512 DAC
OPL3-driven audio system
PC-speaker
8MiB RAM
2500 mAh battery
128 x 150 x 16mm (measured dimensions)
Ports
- CF card slot
- USB port for flash drives
- Connector for VGA output, PS/2 mouse and keyboard
- Connector for 8-bit ISA bus extender
- Headphone jack

Exterior points

The entrance of the system incorporates the next:

LCD panel
Pretty mushy keypad
Energy swap
Disk exercise LED
Battery degree LED
Cost standing LED

At my measured dimensions of 128 x 150 x 16mm, this system may be very compact for what used to require desktop-sized parts almost 40 years in the past.

The photograph additionally exhibits the exterior VGA, PS/2 mouse and keyboard breakout board related.

On the left facet of the Hand386, we see the CF card slot and a USB-port.

The USB port doesn’t have generic USB features that we affiliate with our trendy machines. It’s related to a CH375 chip that solely helps USB mass-storage gadgets like flash drives. Its DOS driver presents the USB system to the working system as a detachable storage media.

A CF card as soon as totally inserted into the CF slot, is flush with exterior of the case. This may current some problem when eradicating it.

To ease removing, I connected a plastic tape pull strip onto the CF card itself so it may be simply pulled out of the slot.

On the precise of the system, we’ve 2 ports.

2×6 2mm pitch Breakout board VGA, PS/2 mouse and keyboard breakout board
2×30 2mm pitch 8-bit ISA bus extender

Very inventive strategy to permit enlargement choices with out compromising the system’s slim kind issue.

The transclucent backcover exhibits the fascinating parts inside. The quilt will be simply eliminated after taking out 8x cross head screws.

Teardown

Now let’s come to the interior parts that makes this tiny magnificence tick.

Again of foremost PCB

Left is the photograph I took and the precise is the labeled model within the gross sales web page.

The most important part right here the battery is glued/taped down with a fairly sturdy adhesive so eradicating it might be difficult in future.

The system doesn’t use as precise 386SX chip however fairly a highly-integrated Ali M6117D System-on-chip (SoC). In response to the Ali M6117D’s datasheet, it has many options resembling however undoubtedly not restricted to:

Intel 386SX suitable core
Reminiscence Controller
Interrupt and DMA controllers
RTC
PS/2 Mouse and Keyboard Controllers
IDE Controller

The vendor has additionally offered the pinout diagram for the breakout boards.

Left for the vendor’s diagram, proper is the 8/16-bit ISA pinout obtained from Wikipedia.

From the diagram, the ISA pins damaged out solely present the everyday 8-bit ISA pins.

The SoC additionally helps a 16-bit ISA bus however I imagine because of kind issue limitations, the 16-bit pins usually are not introduced out externally. However, if these are introduced out, it will little question have offered higher enlargement choices.

The video card chip is a Chips and Tech 65535 that dates again to a minimum of Mar 1994 based mostly on the datasheet. It’s paired with the video RAM chip of Sharp LH6A4260K-60. No datasheet will be discovered for this VRAM chip though Checkit says the VRAM quantity is 256K.

An precise Yamaha YMF262-M OPL3 chip is noticed right here so nice for DOS video games and Midi playback. Within the DOS period, such chips are often included on Sound Blaster Professional 2.0, 16 and AWE household of playing cards to offer FM synthesis capabilities. Nonetheless, there aren’t any Sound Blaster suitable chips current to deal with PCM audio playback.

4x 2MiB AMIC A420616AS-50F 50ns chips present the 8MiB of RAM for the system.

2x SST 39SF512 64KiB CMOS flash chips maintain the system BIOS and video BIOS for the system.

Entrance of foremost PCB

Your complete PCB will be lifted up after fastidiously disconnecting it from the socket of one other PCB that holds the LCD controller and keyboard circuitry.

2 audio system are related from the highest cowl to the primary PCB.

Right here we spot a WCH CH375B. This chip has been recognized for a while within the retro group by means of merchandise just like the lo-tech ISA-USB adapter.

This chip performing in USB host mode has built-in firmware to cope with USB mass-storage gadgets thus assuaging the necessity for advanced USB stack programming on the host system thus very helpful for less complicated DOS methods. A DOS system driver is on the market to deliver out this performance which permits ease of file switch to DOS methods through USB flash drives.

The output of the Yamaha YMF262-M OPL3 chip is shipped to a Yamaha YAC512-M Digital-to-Analog Converter (DAC). These 2 Yamaha chips are often discovered as a pair even on the classic sound playing cards. The analog output is amplified by a 3W Class D Amplifier PAM8403 earlier than being despatched to the audio system.

Show and keypad

The show and keypad part is dealt with by a single PCB.

The LCD show driver is offered by a Realtek RTD2660 chip.

A chip with possible silkscreen “HM82C42” was discovered. Googling doesn’t flip up something however given the quantity of traces going to this chip, I’m going to suspect that is the keyboard controller to the PS/2 interface.

The keypad is made up of a whole silicon rubber piece and PCB conductive pads. This explains the very mushy keypress feeling.

I’d really desire extra tacticle particular person keyswitches however this can considerably increase the part and meeting prices to unacceptable ranges for some.

The flex cable between the LCD panel and show controller board actually worries me. It’s not so apparent within the photograph after the highest cowl is eliminated however when all the things is closed down, the cable might be pressed bent.

The bend was finished as the space between the panel and PCB port is barely shorter than the size of the cable. I have no idea the way it will maintain up over the long run.

With default Home windows 95 setup

It is a 3 minutes bootup and fundamental utilization video based mostly on the offered Home windows 95 picture.

The system struggles with Win 95. I like to recommend not utilizing Win 95 and as a substitute altering it to the older DOS 6.22/Win 3.1 for a greater consumer expertise. A 386SX with its 16-bit knowledge bus is technically even under the minimum requirements for Windows 95 which requires a 386DX with 32-bit knowledge bus.

The viewing angle of the LCD panel is adequate to be used as a palmtop in the event you view it head-on however not far more.

You’ll be able to discover from the video that the interior show is sort of off. It’s famous by the vendor that when an exterior monitor is related to the VGA port of the breakout, the interior LCD will dim (to unusable ranges). The exterior show will even be dim however you must have the ability to modify the brightness/distinction of your exterior monitor.

The system will get very uncomfortably scorching after a while which signifies the CPU load and stress Home windows 95 utilization locations on the system.

With my “docking station”

To completely flesh out the capabilities of this method, I used the ISA bus extender so as to add a 3Com 3C509 10Mbps NIC and a Blasterboard (Sound Blaster 2.0 clone).

With a DOS 6.22/Win 3.1 setup, the system feels extra responsive and undoubtedly a greater consumer expertise. The system nonetheless will get heat however not as scorching as with Home windows 95.

The config.sys and autoexec.bat configuration and drivers used for this setup will be discovered right here. https://github.com/yeokm1/retro-configs/tree/master/laptops/hand386.

A small concern I bumped into is when I’ve an exterior sound card that has its personal OPL chip like a Sound Blaster (clone). As I imagine OPL register instructions are largely solely written to the parallel ISA bus, there shouldn’t be any conflicts as each chips will solely simply obtain instructions. Nonetheless, each chips will now playback the FM audio.

The interior OPL3 chip will nonetheless play the music by means of the interior audio system which will not be desired. As a hack, I simply plugged in a pair of earphones into the Hand386’s headphone jack to silence the audio system.

Different observations

To make use of the ISA bus extender, the Hand386 needs to be turned on first earlier than powering the bus extender. If the bus extender is powered on first, the Hand386 won’t boot.
The onboard RTC doesn’t appear to maintain time nicely. It loses a few minute each 1-2 hours so common NTP sync or handbook time setting is required if time is necessary for you.
From a full-charge, I get about 1.5h on Win 3.1 of utilization earlier than the low battery warning comes on and the system will shut off completely shortly after. However, the battery lifetime of this system shouldn’t be in comparison with trendy laptops and I’m comfortable with it as-is.
The battery can drain quicker than the charger can provide below heavy load.
Mouse assist is disabled by default when the BIOS is (intentionally/randomly) reset. That is talked about within the consumer handbook.
With exception to the glued down battery, the system appears very repairable. No bizarre screws and all the things is accessible. Floor mounted ICs are positioned far sufficient from one another that remodeling them ought to have minimal concern.
My system’s show controller/driver/panel really failed after some days of use. Upon verifying the fault by means of a video I despatched them, they agreed to ship me a alternative for my faulty unit. I’ve to say their exemplary customer support.

Instructed enhancements

I despatched this checklist to the Hand386 vendor. It’s just a few concepts I can take into account for addition if I used to be the designer of this system. Not all the things is feasible as till one will get to the engineering side, it’s arduous to inform if these options are possible to be added.

Audio
- BIOS disable possibility for onboard OPL3 as some customers like me have an exterior Sound Blaster or OPL-capable card.
- Quantity management for onboard OPL3
- Add Sound Blaster suitable PCM audio assist utilizing chips from ESS or Crystal.
Energy
- Use USB-C port for energy provide as a substitute of barrel jack
Consumer interface
- Add a trackpad/ball or some form of interface to regulate the mouse
- Mouse assist enabled by default within the BIOS
Show
- Skill to disable onboard C&T 65535 ISA graphics chip if a consumer has an exterior ISA graphics card
- Eradicate the VGA dimness when attaching an exterior monitor.
- If it doesn’t value an excessive amount of, change the show with one with higher viewing angles.
Warmth/Casing/Ports
- Add some vents within the casing or heatsink/fan. Gadget can get uncomfortably heat after extended use particularly if utilizing Home windows 95 or gaming.
- 386 within the laptop computer kind issue like Book8088 could be simpler to make use of and have higher thermal cooling and port choices
- Add PCMCIA assist. Current bus extension with ribbon cable is sweet however will be troublesome to take away generally with out bending the pins.
- Some means to simply take away the CF card.
Software program
- Home windows 95 shouldn’t be optimum for 386SX. Ought to preinstall with DOS 6.22 and Home windows for Workgroups 3.11.
- Change CH375DOS.sys with CH375286.SYS for extra steady flash drive assist and efficiency. See this driver comparison video from the Youtuber THE PHINTAGE COLLECTOR.

Regardless of the problems I identified, I’ve to say this product may be very nicely made and has gotten many issues proper. It’s an excellent job for a primary iteration of such a product.

As an embedded engineer myself who has labored on product design tasks, I can admire the problem in designing for manufacturing such a product from scratch into such a compact bundle. 386 machines was once full-sized desktops or very thick laptops.

There are a number of complaints on the value of the system at about US$200. Given the comparatively small manufacturing of run of this product for a distinct segment market, this value is definitely superb given the low manufacturing portions of tons of? (undoubtedly no more than low hundreds) and with an injection moulded case as well.

The quantity {of electrical}, mechanical and software program engineering effort that went into this product shouldn’t be small for such a distinct segment product. From trying on the mechanical/board design and part datasheets, I’ve certainly discovered fairly a bit on how such a product will be designed and definitely have gained helpful information.

I’ve to commend their glorious customer support. They’re very responsive and useful in my queries of technical particulars of this system. To not point out a alternative once I confronted the show defect. Positively not a vapourware product.

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